The grim discovery was reported about 1:30 a.m. after transients encountered the deceased woman just south of the Ocean Boulevard Bridge, according to Lt. John Kanaley of the Long Beach Police Department. The river flows into the Port of Long Beach near the scene.
It was not immediately known how the unidentified woman died, the lieutenant said. Police were investigating whether she had passed away at the location where her body was found or elsewhere.
The transients who made the discovery reported seeing a dark-colored SUV leaving the area. A vehicle matching that description was later pulled over and the driver was detained, but that person has not been connected to the case, police said.
There were no obvious signs of trauma on the body, investigators said. She was described only as being in her 30s and fully clothed.
Members of Long Beach's Public Safety Dive Team searched the nearby waters as L.A. County coroner's officials removed the body from the scene.
"Because the cause of death is unknown at this time, homicide (detectives) will investigate and determine the cause of death," said police Sgt. James Richardson.
Long Beach dive team just arrived at crime scene where woman's body was found on rocks along LA River. #abc7eyewitness pic.twitter.com/tjs2TNjuR3
— Marc Cota-Robles (@abc7marccr) April 6, 2017