Authorities said Kevin Rodriguez has been missing since about 7 p.m. Saturday.
"He slipped out the front door - I guess he was still upset over the disagreement - and walked away from the house," said Sgt. Kyle Kirkman of the Los Angeles Police Department.
Police on Sunday roped off a portion of the 1500 block of East 22nd Street in the search of the boy. Officials have been searching from Compton to Long Beach, even bringing out a canine and a helicopter at one point.
Police and family members were very concerned about the missing boy who speaks little English. He has been in the U.S. for three months and primarily speaks Spanish.
"There are some unsavory characters in the world," Kirkman said. "We're hoping that he ended up going to a friend's house and spent the night over there or in an area where he's safe. It's a great concern to us because of the time that went by now."
Police said he had been on a field trip with a youth group, hiking and spending time at the beach.
Family members said he has never run away before.
"It's stressful not knowing where your kids are," said the boy's uncle, Rick Rodriguez. "You don't know what the outcome is going to be, so it's really concerning."
Rodriguez is Hispanic, about 4 feet, 5 inches tall and weighs 100 pounds. He has black hair and brown eyes and was last seen wearing a red T-shirt and blue pants. Police added that the boy was not wearing shoes. There were some questions about the boy's age, but it was later determined that he's 9 years old.
Anyone with information is urged to call the LAPD at (877) LAPD-24-7.