BOSTON -- Somerville police launched a frantic search for a 5-year-old boy who they said went missing early Friday after becoming ill at school and who apparently took off, but he was found about an hour later.

Jonathan Escobar, 5, a student at the Prospect Hill Academy Charter School at 15 Webster Ave., was described as being Hispanic, about 3 feet tall, stocky and carrying a Spiderman backpack.

"A citizen reported that the saw this child walking alone. They were concerned for safety. The woman called 911, got the child to stay with her for few a few minutes, and we had police units on the scene in under a minute," Somerville Police Deputy Chief Paul Upton said.

School officials said the boy was sick with a fever and was going to be sent home at about 8 a.m. when he took off.

"The child arrived this morning at about 7:46, per the normal routine. He went to his classroom, as he does every day. He informed his teacher that he was not feeling well," said Principal Jed Lippard.

"Prior to someone coming to pick him up, he left the building," Upton said.

Upton said the boy was found on Medford Street, about halfway between his home and the school.

"It is possible he was confused. He was told he was going to be dismissed to go, and he may have interpreted that as leave on his own. He's 5 years old," Lippard said.

Upton said the child was seen on surveillance cameras in nearby Union Square.

The boy was taken to a local hospital where he was reunited with his family.

"There is no foul play at all expected. We don’t believe anything unusual happened here other than a child walking away from the school," Upton said.