State Rep. Mike Connolly expressed concern about the incident, saying “it could have been much more catastrophic.”

The MBTA's Green Line Extension is back in operation after a derailment Tuesday afternoon sent several passengers to the hospital and caused another headache for a transit agency that can't seem to catch a break.

The shuttle buses that replaced train service all day Wednesday have been phased out, the MBTA said in a social media post at about 10:30 a.m. Thursday.