Media reports and Twitter accounts on Friday night said that shots have been fired in Watertown, Mass., and an ambulance was viewed rushing to the scene.
The Boston Globe reported that the Boston Marathon suspect has been corralled.
Residents have been evacuated around the area where the shots were fired.
“Get ready to get behind something solid,” a police officer told WCVB TV.
And ABC reported that bystanders shouted “go get em!” as police responded. to the scene.
Television footage is showing emergency and military vehicles speeding through town Friday evening.
It wasn’t immediately clear whether authorities had found 19-year-old college student Dzhokar Tsarnaev ((JOH’-kahr tsahr-NY’-ev).
Authorities are telling residents of the area to stay indoors.
The Associated Press contributed to this report.