WILMINGTON, Ill. — Rescue crews searched the rushing Kankakee River yesterday for a young Marine, recently home from Iraq, who disappeared while trying to save his 4-year-old nephew.

The boy’s mother and an unrelated man drowned after jumping into the river on Sunday in an effort to reach the boy. The child, Brian Santoyo of Chicago, was eventually pulled out and resuscitated.

Authorities said the Santoyo family and some friends had been on a fishing outing near a Kankakee River dam, about 45 miles southwest of Chicago.

The river can be particularly dangerous in that area because of the undertow and eddies from the dam, Wilmington’s police chief, Wally Evans, said. Over the last 25 years, between 15 and 20 people have drowned there.

“The child apparently got caught in the undertow,” Chief Evans said. “You see a 4-year-old go in the water, and then someone goes in, and then someone else goes in. I’m telling you, it’s terrible here. It’s really terrible.”

Witnesses said family members and friends formed a human chain to try to rescue Brian, but the current was too strong.

The boy’s mother, Delia Santoyo, 27, and Alberto Medina, 28, of Chicago, both drowned. Sergeant Jafet Santoyo, 23, disappeared in the water and was presumed drowned, Chief Evans said.

Family members said Jafet Santoyo, a Marine, had returned recently from a tour in Iraq.

Andres Alvarez, 29, finally reached the boy and his mother and pulled them from the water but was unable to resuscitate the woman, authorities said.

The boy was in stable condition yesterday at Children’s Memorial Hospital in Chicago. His father, Jose Santoyo, 28, was treated at another hospital and released.