COSTA MESA — A four-vehicle collision on the northbound 405 freeway, at the Harbor Boulevard on-ramp, left two people dead Friday evening, Jan. 5, and traffic along one of the busiest stretches of freeway in the country snarled, the California Highway Patrol said.

Shortly after 8:30 p.m., a Volkswagen sedan in the carpool lane hit the center divider, according to the CHP. Three other vehicles were involved in the crash, including one described as a Dodge Charger, though it was unknown whether those vehicles crashed before or after the Volkswagen hit the center divider, a CHP dispatcher said.

Those killed were a man and a woman who were riding in the same vehicle, Costa Mesa Fire Department Capt. Chris Coates said. Their names were withheld pending notification of next of kin.

Another man and woman were injured, Coates said. They were transported to a hospital for treatment, where their conditions were not immediately disclosed.

Information on the ages and identities of the people who died – as well as which vehicle the victims were in – wasn’t immediately available.

It was too early to know more details about how the crash happened, the dispatcher said.

A SigAlert was declared by the CHP at 8:47 p.m. after authorities shut down all northbound lanes except one, and traffic backed up for miles.

At 9:05 p.m. the CHP updated the SigAlert by reopening the number 5 and 6 lanes, those on the right side of the freeway. All lanes were cleared at 11:32 p.m., according to the CHP and the SigAlert was canceled.

City News Service contributed to this report.