Two days after a derailment on the MBTA’s Green Line near Lechmere Station, the agency announced Thursday that regular service has resumed and shuttle buses phased out.

The MBTA said necessary repairs were made to the Green Line Extension and a test train successfully operated through the area before service was restored around 10:30 a.m. Trains are once again carrying passengers between North Station and Union Square and between North Station and Medford/Tufts.

Seven passengers suffered minor injuries in Tuesday’s incident near Lechmere Station, in which the derailed train car breached over the track toward oncoming train tracks.

“Obviously, this is a really shocking incident,” said state Rep. Mike Connolly, who represents the 26th Middlesex District, covering the T stations at Lechmere, Union Square and East Somerville.

“Part of what makes this so alarming is had a train been traveling in the other direction, it could have been much more catastrophic than the incident we saw,” Connolly added.

He also expressed concern about the response to the incident. Connolly said though there is an emergency egress staircase nearby, some of the 50 passengers on board the derailed train were confused about safe evacuation and medical treatment.

“There were some concerns regarding triaging the different injuries, and sort of a lack of direction,” he said.

The MBTA said a preliminary focus of its investigation shifted to operator error when it was determined there were no equipment issues.

The National Transportation Safety Board continues to investigate and document the scene, but a spokesperson said it does not determine or speculate about the cause of the accident. A preliminary report will be available within 30 days. A probable cause of the crash, along with any contributing factors, will be detailed in the final report, which is expected in 12-24 months.

This latest incident comes at a sensitive time for the MBTA, which was already under federal scrutiny for ongoing safety issues. Last month, the Federal Transit Administration sent a warning letter to the agency, citing 27 maintenance vehicle derailments so far this year.

Connolly said it is frustrating because the MBTA seemed to have turned a corner and created momentum toward building the service the public deserves.

On Thursday, MBTA General Manager and CEO Phillip Eng apologized for the incident and emphasized the agency’s commitment to safe, reliable service.

“I want to acknowledge the efforts of the MBTA team that safely cleared the incident train, and repaired our track, signal, and power infrastructure, allowing us to resume service today,” Eng said in a statement. “Know that we share a common goal with the NTSB, FTA, and DPU and are fully committed to continuously improve and deliver safe and reliable service to all that we serve.”