The following is the account of this event extracted from Chapter XXVIII of Aduarte's Historia, The Philippine Islands, 1493-1803, Vol. 1, no. 32, Emma Helen Blair, et. al.
On the eighth of June, the first Sunday after the most Holy Trinity, a great misfortune occurred in the revolt of some Indians of the province of Nueva Segovia. Turning their backs on the faith, they gave it up and fled to the mountains - a thing which caused great grief to the ministers of the holy gospel.
In that province, above a village named Abulug, near a river which comes down from the mountain, two villages had been formed by gathering the inhabitants together. They were called Nuestra Sefiora del Rossario de Fotol, as has been recounted in this history, and San Lorenzo de Capinatan. In the latter there lived some Indians known as Mandayas, a wild and fierce tribe whose native abode was in mountainous places about the bay of Bigan in Ylocos.
The religious ministered to them and assisted them in their necessities, taught them the law of God, and baptized many people, for these people generally asked holy baptism from them. Their evil nature, which was perverse and restless, and their affection for their ancient places of abode so attracted them that it seemed as if in that village they were caught fast by the hair. Three times they endeavored to escape to the mountains; and though they were prevented twice, and their efforts came to nothing, this last time they so planned their attempt, and kept it so secret, that they carried out their evil purpose. With this object, they stirred up the old inhabitants of Capinatan, and persuaded those of Fotol, bringing them to join them by means of threats and prayers. Some of the people of Fotol became so obstinate that they were worse than the Mandayas, the first movers of the insurrection. Afterward the Mandayas who were in Capinatan rose; and two of them, Don Miguel Lanab and another chief named Alababan, set the enterprise in motion by going to the church to speak to the religious who was there at the time. This was father Fray Alonso Garcia, a son of the convent of San Pablo at Valladolid, who had said a first mass in the village of Fotol, and a second in Capinatan, and was now at dinner with brother Fray Onofre Palao, a lay religious from the convent of Manila. They were seated at their meal in a little corridor of the house.
Their assailants came up, and each one standing beside the religious whom he was to decapitate, they made a pretense of asking permission to go to some villages on their ancient lands. Father Fray Alonso, who had but recently come, referred the request to the regular minister of the village, and asked them to wait till he should come, because he was in another village. At this point Alababan raised his arm, and with his balanao or knife he struck such a blow on the neck of Fray Onofre that he cut off his head to the backbone, leaving it hanging by only a little bit of skin. Don Miguel Lanab, who had not acted so promptly, lifted his knife, and father Fray Alonso naturally raised his hand to protect his head. The knife cut through this and the blow went on and reached his head. Father Fray Alonso rose from the table and fell on his knees like a gentle lamb; and the Mandaya traitor repeated the blow, giving him another on the head.
The Indian boys who served at the table began to scream; and the transgressors, that they might not be caught in so perfidious an act, made their escape. Some Indians who were ignorant of the conspiracy came, and took father Fray Alonso to the house of a chief, where some medicines were applied to the wound. As they were preparing a barge in which to take him down to the village of Abulug, the Mandayas came, and prevented them from doing so by threats. They took him back to the house of the chieftainess: and while father Fray Alonso was exhorting the people to come back to obedience, and expounding to them the evil of which they were guilty in apostatizing from the faith, three Mandayas came in, and with their keen balanaos or knives cut to pieces the confessor of Christ. They afterward threw out the pieces from the house, to be eaten by the swine who were there.
As a result of this atrocious deed, the Mandayas rose in a body and roused the Capinatas; and, coming down to Fotol, they forced the people there by menaces to flee with them to the mountains. They set fire to the churches, and, as members of Satan, they defiled them by a thousand sacrileges. They struck off the head of a Christ, and cut the body down the middle, dividing it into two parts, which were afterward found by the religious who came to bring them back to obedience. The religious buried these, the uprising of the Mandayas (of whose severe punishment we shall soon hear) allowing no opportunity for anything else.
With regard to Fray Alonso Garcia, several matters worthy of remark were noted. The first was this. Some months before, while he was living in the convent in Capinatan, he one night had put himself into the posture of prayer in the dormitory, with his breviary in his hand. At this time the convent was disturbed by an imp who caused so much trouble that he would not give the religious any rest, and from whose visitations there was not in all the convent any place that was free. He disturbed them in the dormitory, he made a noise in the cells, he feigned the noise of a struggle in the church; and sometimes he let himself fall with a clatter that was heard in the village, and he would throw himself down from the choir. He used to walk up and down in the church, and he made his appearance in the larders, where he broke all the plates there were; he made a noise under the beds, and struck the heads of the bedsteads; and sounded the strings of a harp which they had for use at masses on some feasts. This disturbance lasted until the breaking-out of the uprising, and must have been a prognostication of it, and a sign of what the devil was devising to disquiet the Christians of this village.
Now while father Fray Alonso was praying, the imp came to him, invisible to everyone in the dormitory, and struck the father a heavy blow, so that he felt pain in the same hand and wrist, in the place where the blow afterward fell which cut it off. This was the first of the things referred to. The second was that he thought so little of himself, and had so little confidence in his own works, that he was accustomed to say that if he did not die by some fortunate blow which should take away his life and despatch him to heaven, he did not know whether he should go there. This he said because of his humility, and the event was as he said. Another matter was that, although father Fray Alonso was not a very skilful linguist, and not one of those who had made the greatest progress in speaking the language of that tribe, yet when he was wounded by the first blows and was urging the Indians not to flee, and telling them of the harm which would come to them if they did so, he spoke with such elegance and precision that the Indians were amazed to hear him; and they noted this as a striking fact at the time, and told of it afterward. He was very charitable, and was in the habit of praising all and of speaking of the defects of himself alone. He came to the Philippinas in the year 1622, and lived in the province of Nueva Segovia- where, in his third year, he met with the happy death which keen knives, directed by hands of apostates from the faith, bring to ministers of the holy gospel.
The intermediate chapter of 1628 made mention of these two religious in the following words: "In the province of Nueva Segovia father Fray Alonso Garcia, a priest, and brother Fray Onofre Palao, a lay brother, died happily by the hands of impious apostates, an uprising of the Indians to whom they ministered having occurred."
In the place where father Fray Alonso was cut to pieces, there was afterward raised in his honor a small shrine. The Indians were brought back in the following year, and this tribe used devoutly to frequent this shrine. The dwelling of the religious had stood where Fray Onofre had been killed, and here it was erected again.
Since the first building was burned, it was supposed that the fire had consumed his body at the same time - although some Spaniards have some small bones which they value, believing that these are his, because they found them where he was decapitated.
Philippines News Agency archives
Chapter XXVIII of Aduarte's Historia (via The Philippine Islands, 1493-1803, Vol. 1, no. 32, Emma Helen Blair et al, 1911, University of Michigan Digital Library).