GILROY -- Police said Tuesday that a naked man who was tackled by restaurant patrons after entering the eatery holding and shaking an infant last week is the baby's father, appeared to be under the influence of stimulants and suffered a heart attack while he was being handcuffed.

Los Banos resident John Anthony Ruiz, 42, remains in the hospital in critical condition after the Friday morning incident at a restaurant on the 8100 block of Monterey Street. According to police, Ruiz entered the eatery "acting bizarrely and making nonsensical statements" and "holding and shaking the baby."

"Patrons of the restaurant distracted Ruiz, allowing others to free the baby from his grasp," states a police release. "Ruiz responded violently and started advancing toward the baby at which time several patrons tackled Ruiz and held him down until police officers arrived on scene."

Ruiz resisted arrest even as officers used pepper spray in an unsuccessful attempt to subdue him. After a struggle, officers got handcuffs on Ruiz at which point he "stopped breathing and apparently suffered from cardiac arrest," according to the report.

Medical personnel who were called to the scene were already waiting outside, and immediately worked on Ruiz and transported him to a hospital. No further information about the suspect is available at this time, said Gilroy police.

The baby was also taken to a hospital for evaluation and released with no observed injuries. The 6-month-old boy was taken into custody of the Santa Clara County Department of Family and Children Services.

Police said Ruiz appeared to be under the influence of a stimulant during the incident, and an unspecified quantity of methamphetamine was later found in his possessions. He had recently been released from jail where he was being held on a parole violation.

Police are seeking numerous charges against Ruiz, including felony child endangerment, resisting arrest, possession of a controlled substance and being under the influence of drugs.

It has not been determined whether the infant's mother will face any charges.

Because of Ruiz's medical problem while being taken into custody, the Gilroy police internal affairs department is also conducting an investigation into the incident, along with Gilroy detectives and the Santa Clara County District Attorney's Office.

Anyone with information about the incident is asked to contact Gilroy police at 408-846-0350.

Contact Eric Kurhi at 408-920-5852. Follow him at Twitter.com/erickurhi.