SAN DIEGO — Twenty people were rescued from a flooded drainage tunnel in San Ysidro on a rainy Thanksgiving night and a body was found in the water of a beach near the west end of the Tijuana river Friday morning, authorities said.

Around 11 p.m. Thursday, a Border Patrol agent found three people attempting to enter the United States from Mexico through a border drainage tube about two miles west of the San Ysidro Port of Entry, according to U.S. Border Patrol public affairs.

Those three people told the agent that more people were inside the drainage tub and the San Diego Fire & Rescue Department was called to the scene to help rescue the remaining people because water in the drainage tube was beginning to rise.

Agents pulled one woman to safety after hearing her yell for help and she informed them that others had also fallen into the drainage tube. A manhole was located nearby and emergency personnel pulled 13 people to safety. Seventeen people were evaluated at the scene and seven were taken to nearby hospitals for further treatment, Border Patrol officials said. One person was taken to UC San Diego Medical Center for treatment of serious injuries and the others were less seriously hurt, SDFRD spokeswoman Monica Munoz said.

Emergency personnel searched the drainage tube, but didn't find anyone else inside at the time. About two hours later, agents heard a woman yelling for help in the same drainage tube.

Emergency personnel rescued her and also found two other people near the exit of the tube. The woman was taken to a nearby hospital, but the extent of her injuries was not immediately available.

Of the 20 suspected illegal immigrants, 19 were Mexican nationals -- 15 men, 3 woman and one teenage boy -- and one man was a Guatemalan national, Border Patrol officials said.

Around 2:40 a.m., a Border Patrol agent found a person's body in the water on a beach near the west end of the Tijuana river mouth.

The agent contacted the San Diego County Sheriff's Department and the San Diego County Medical Examiner's Office took custody of the body for autopsy and identification purposes.

The sheriff's department was investigating the death and it was not immediately clear if it was related to the smuggling incidents.