(CNN) — The father of a Baton Rouge deputy who survived the deadly July 17th attack on police officers, posted an update and a touching story about his son.

On his Facebook account, James Tullier wrote that his son, Nick Tullier, an East Baton Rouge Parish sheriff’s deputy, still remains on life support.

Tullier, 41, was shot in an attack that killed three law enforcement officers and injured two others.

On Tuesday, his father shared a good Samaritan story regarding his son that occurred just a day before the attack. His Facebook post received more than 18,000 reactions and 8,500 shares by Wednesday morning.

A Good Samaritan

The following account comes from his father.

After finishing a day shift on July 16, Deputy Tullier had been heading home when he came across a woman on the side of the road with a flat tire.

“Instead of just passing her by and let her fend for herself, Nick pulled over to help,” his father wrote. “He called his fiancé to let her know he would be delayed getting home and that he had to stop to give assistance.”

The stranded woman had small children with her. So Tullier took out a spare tire from his sheriff’s car and put it on the woman’s car.

“He then followed her all the way back to her home in Baton Rouge making sure she and the kids got home safe… Nick then took his spare tire back off the lady’s car and returned it to his unit,” wrote his father.

The very next day, Tullier was critically wounded in the shooting.

Tense times in Baton Rouge

The gunman in the shooting was identified as Gavin Long, a 29-year-old black man from Kansas City, Missouri. Long was a former Marine who spent time in Iraq, he left behind a manifesto concerning police corruption.

The ambush had come two weeks after a Baton Rouge police officer had shot and killed Alton Sterling, a black man, outside a convenience store in the city on July 5. Sterling’s shooting kicked off days of national turmoil.

During the shooting, Tullier had been in his patrol car running the license tag of the gunman’s car when Long opened fire, critically wounding the deputy.

When Tullier’s family gathered at the hospital, his fiancé told them about his act of kindness in helping a woman with the flat tire.

A chance encounter

Later on, his father attended the service for Montrell Jackson, one of the Baton Rouge police officer who was killed in the shooting. Jackson, an African-American police officer, had left behind a wife, a four-month-old son and an emotional plea for his community to heal on his social media account.

After the service, the elder Tullier chatted with Jackson’s family when someone motioned him over saying, “Come here, I’ve got something to tell you.”

The man introduced him to a woman standing next to him who turned out to be Jackson’s wife’s niece. The woman told Tullier the same story his son’s fiance had told him. She told him that his son helped her with the flat tire the day before the shooting.

“Chills went through me,” wrote James Tullier. “This was flat out unbelievable.”

They hugged each other and the woman thanked him saying that his son was “a life saver and a hero.”

“That’s always been in his heart to help in times of need,” his father wrote. “Our Nick didn’t see color. What he saw was a lady in need and small children there too. His heart told him he had to stop and give assistance to a fellow human being. That’s our Nick.”

CNN’s Dave Alsup contributed to this report.