SAN ANTONIO (KSAT.COM) – An Amber Alert was issued Monday for an 11-month-old baby boy believed to have been abducted by his father.

Police are looking for Jonathan Jose Guillen Jr., who is believed to be in grave or immediate danger.

The infant’s 23-year-old father, Jonathan Guillen, took the boy after he fatally wounded the infant’s mother’s boyfriend during an argument Thursday, police told San Antonio’s KSAT-TV.

Jonathan Jose Guillen, Sr. (San Antonio Police/KSAT-TV)

Jonathan Jose Guillen, Sr. (San Antonio Police/KSAT-TV)

The suspect is driving a 2002 black Chevrolet Trailblazer with Texas license plate 7CZTJ. He is 5 feet 8 inches tall, weighs 185 pounds and has brown hair and brown eyes.

Anyone with information on the abduction is urged to call the San Antonio Police Department at 210-207-7660 or 911.