The HOV lane on the Southeast Expressway was closed around 7 a.m. following a multi-vehicle crash during the Friday commute, according to Massachusetts State Police.
The crash happened on Interstate 93 northbound near Exit 14, Morrissey Boulevard in Dorchester, and was causing traffic delays all the way to the Braintree split.
NBC10 Boston's Natasha Verma reported the cars involved were at a stand still for at least an hour, which caused a 5-mile backup on the northbound side.
The HOV lane has since reopened but there was a 30-minute delay as of 8 a.m. Friday.
Police say there are minor injuries in the crash.
No other information was immediately available.