A tractor-trailer struck and killed a pedestrian on Interstate 95 in Dundalk shortly after 2 p.m. Thursday, forcing the closure of all the highway's northbound lanes for about three hours and creating a large tie-up in evening rush-hour traffic.

The 36-year-old man's identity was not released Thursday because authorities had not yet notified his next of kin, said Sgt. Jonathan Green, a spokesman for the Maryland Transportation Authority Police Thursday night.

Green said it was not clear how the accident had occurred, or why the man was walking along the interstate.

"Our goal is to both conduct a thorough investigation and to get the roadway open as soon as possible," Green said. "In the meantime, we encourage people to find other routes."

The lanes were reopened just after 5 p.m. Northbound traffic had been diverted off the highway at exit 57, Boston Street, and directed to proceed through two intersections before getting back onto I-95 just south of Dundalk Avenue.

A bulletin from Baltimore Firefighters Union Local 734, some of whose members were summoned to the scene of the accident, warned motorists to "expect major delays for several hours" after the accident. It said travelers should avoid northbound I-95 between the Fort McHenry Tunnel and Eastern Avenue until police investigators have finished their work.

A separate accident late Thursday afternoon shut down all lanes of eastbound Interstate 70 and sent two people to Maryland Shock Trauma Center for non-life-threatening injuries, police said.

The accident happened about 4 p.m. just before to the Baltimore Beltway. Four vehicles were involved in the rear-end crash, including two SUVs, a box truck and a pickup trick. Police said the pickup was carrying hazardous chemicals, including chlorine, that had to be cleaned up.

nick.madigan@baltsun.com

Baltimore Sun reporter Jessica Anderson contributed to this article.

jkanderson@baltsun.com