This post has been updated.

Maryland State Police are investigating a bus accident that happened Friday afternoon on northbound  I-95 near exit 89 about 40 miles north of Baltimore.

According to a preliminary investigation, it appears the bus, operated by Megabus, moved onto the right shoulder of the interstate and struck the guardrail. It remained upright. No other vehicles were involved in the incident, which happened just after 3:30 p.m.

“ is aware that an incident has occurred on Interstate 95 near Webster Village, Maryland,” the company said in a news release. “We are currently working with local officials to gather details of the incident. Safety is’s number one priority.”

Maryland State police said five of the 68 passengers on the New York-bound bus have been transported by ambulance to Harford Memorial Hospital as a precaution. The bus had left the District bound for New York City earlier in the day.

Authorities had shut down all traffic lanes, but all have since been reopened.

Troopers and Maryland Transportation Authority officials arranged for shuttles to take the passengers to a nearby location until a replacement bus arrived.

A spokesman for Megabus said Friday evening that a replacement bus had been brought in and that the passengers at the scene continued on their trip.