An Amber Alert has been issued by the police as they pursue 41-year-old James Calvert, a man suspected of killing his ex-wife and taking his 4-year-old son, Lucas, from his mother's house in Tyler, Texas. 

Detective Doyle Lynch says the suspect is believed to be driving a silver and/or grey 2000 Buick LeSabre sedan, with Texas license plate DP4G858. It is believed that the child is in grave and immediate danger. 

Lucas, a white male born on Feb. 26, 2008 is 3 feet tall, weighs 30 to 40 pounds, has brown hair and brown eyes. He was last seen wearing a long sleeve blue sweatshirt, grey sweat pants, and silver caps on some teeth.

James Calvert is a white male born on Dec. 3, 1970. He is 5 feet, 9 inches tall, weighs 185 pounds, has brown hair and brown eyes.The suspect was last heard from in Tyler Texas.

If you have any information regarding this abduction, call the Tyler Police Department at (903) 531-1000.