This story was updated at 2:05 p.m. on Thursday, June 20.
SEALE, Ala. (AP) -- Investigators say the driver of an SUV that plunged from an overpass and killed three teens had fallen asleep at the wheel.
Three Phenix City, Ala. teens were killed June 9 when the GMC Envoy they were riding in hit a guardrail and fell 40 feet from a bridge.
Investigators tell the Ledger-Enquirer of Columbus (http://bit.ly/180x8NS ) the driver was asleep at the wheel and over-corrected when he woke up. Officials say the vehicle swerved across the bridge and into the guardrail.
The vehicle was carrying seven people at the time of the crash.
Three teenagers have died and four people were sent to the hospital after a car overturned off a bridge 15 miles south of Phenix City on Sunday afternoon.
The crash took place on U.S. 431. According to authorities, Marvin Anthony Alexander, 37, of Phenix City, was driving a 2003 GMC Envoy when he lost control of the car. The car struck a guardrail and overturned off the bridge at approximately 3:10 p.m.
Alexander, Joann Robinson Bellamy, 58, Kelsey Bellamy, 17, and Tramain Evans, 9, were transported to area hospitals for their injuries.
Darius Washington, 15, Chelsea Tolbert, 15, and Katrina Robinson, 16, all of Phenix City were pronounced dead at the scene of the accident.
Although circumstances surrounding the crash are under investigation, Troopers say speed was a factor. Nothing further is available as Alabama State Troopers continue to investigate.