[UPDATE Friday, 9:22 p.m.]
NECN and others are reporting on Twitter that Boston Police have a suspect in custody in the standoff on Medford Street. They are also reporting that there have been no injuries and that police are clearing the scene.
[UPDATE Friday, 8:57 p.m.]
Boston Police are in a standoff with a barricaded suspect at 170 Medford St. in Charlestown.
According to BPD spokesperson Officer Neva Coakley, police received a call about the incident at 6:26 p.m. One shot was fired, but there are no reported injuries at this time.
Police have evacuated one building and were about to evacuate another building at about 9 p.m., Coakley said.
She had no further details and was not sure which streets might be closed down.
According to scanner reports, police were evacuating residents in adjoining units and contacting residents in the surrounding area to warn them against looking out windows.
Several Twitter users following the incident on police scanners and otherwise have reported that Boston SWAT is on the scene and that State Police have also been called in.