Multiple Orange Line trains were temporarily taken out of service Thursday after being vandalized overnight, the MBTA said.
A T spokesperson said the vandalism consisted of "malicious damage to windows."
"We will be operating with longer headways this afternoon due to a limited number of trains," the MBTA said on Twitter shortly before 2 p.m. "Multiple trains were vandalized last night and repairs are in process."
On its website, the MBTA says subway schedules are determined by headways -- the time and space between each train. Anytime a train is pulled out of service, dispatchers need to adjust the space and time between the other trains in service.
The T apologized for the inconvenience and said it was working to get the trains back into service "as quickly as possible."
Around 3:15 p.m., the MBTA provided an update saying that repair work and window replacements had progressed at a good pace and they expected to have enough Orange Line trains for the afternoon commute to keep up with the existing schedules.
No further information was immediately available.