(KMOV) – Police are investigating an accident that left one man dead and three others hospitalized following a single-vehicle accident in north St. Louis Monday morning. According to authorities, four men between the ages of 20 and 30 years old were traveling southbound near the 3400 block of N. Kingshighway and Lexington around 4:00 a.m. when the driver lost control. The driver attempted to swerve in an attempt to avoid another vehicle and as a result lost control and slid out of control, police said. The vehicle then hit a curb before slamming into the center median at Lexington St., causing it to flip over. According to authorities, there of the occupants were ejected from the vehicle. Robert Gilbert, 31, was pronounced dead at the scene. The three other occupants were transported to an area hospital where all but one was listed in critical condition. Kingshighway was shut down in both directions just south of Natural Bridge. The northbound lanes were back open by about 6:45 a.m. Officials said the southbound lanes would reopen by 7:15 a.m. at the earliest. The investigation remains ongoing.