Five passengers were taken to Harford Memorial Hospital as a precaution, but police said there appeared to be no visible injuries, MSP spokesman Greg Shipley said.
Two of northbound lanes reopened by 5 p.m., and all were open about an hour later, although traffic remained slow during the time investigators remained on the scene, police said.
Megabus spokesman Sean Hughes said the company is working with local officials to gather details of the incident and that safety is the company's number one priority. The bus was traveling from Washington to New York, he said, and a replacement bus had been dispatched to pick up the stranded passengers. Police said it last stopped at White Marsh, where 25 passengers boarded.
The crash occurred shortly before 3:45 p.m., and the northbound lanes near exit 89 were closed because of the number of passengers who had to disembark from the bus and wait on the shoulder of the highway for transportation, Shipley said. They have since been taken to a nearby park and ride by state troopers, police said, and arrangements are being made to move them to the Maryland House rest area until a replacement bus arrives.
The bus, which remained upright after the collision, had a mechanical problem that required it to be towed rather than driven from the scene, Shipley said. No other vehicles were involved, he said.
Police said they have not determined the cause of the crash and that they were continuing their investigation.