Police spent the afternoon searching Gonzales' house, where multicolored Christmas lights hung on the eaves.
The 8-year-old boy was taken to Corpus Christi to be interviewed by police and would be released to his grandparents, Bueno said.
Gonzales worked for the Alice Police Department from 2000 to 2007 and three more years beginning in 2008.
State records show he also has worked for the Jim Wells County Sheriff's Office and police departments in Freer and San Diego. Bueno said he also had been employed by the U.S. Border Patrol.
"It's a tragic day when a city employee that is charged with upholding the law takes that law into their own hands, and people are hurt," City Manager Ray De Los Santos said, "but make no doubt about it, today had the potential to be much worse than it has been."
The day's events stunned the close-knit Alice Police Department, which has about 50 employees.
"To some of my people here, it still hasn't sunk in," Bueno said.
He didn't know Morin personally but had met her when she attended department Christmas parties with Gonzales.
"I like to say we're family," Bueno said. "It does put a sad chapter in our lives. I've been here 34 years. This is my second home. To see something like this is very difficult, but we want to go on, and we must continue to provide our community with the best service we can."
A staff meeting was planned for today, with counselors and a priest expected to be available to employees.
Staff writer Mike Baird contributed to this report.