Police confirmed the officer was taken to the hospital, but his injuries weren't believed to be life-threatening.
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A suspect was taken into custody after shooting the officer and barricading himself in an apartment.
“Those individuals, when they made eye contact (with the officer), they immediately got up, clutched at their waists," Gross said. "These officers (are) trained (in the) characteristics of armed gunman. Eventually, officers gained entry into a common hallway, where they were immediately met with gunfire."
Three people in total are in custody, and no further shots were fired at police after the initial shots at the officer.
Neighbors found themselves locked either in or out of the active perimeter during the chaotic situation, all coming in the midst of what seemed like a routine Sunday afternoon.
"Just to see this happening in our neighborhood is crazy," Yash Vazirani said.
The shooting was followed by an incoming presence of SWAT officers and hostage negotiators, creating a concerning situation for residents.
"We were walking by as the rush of cop cars and SWAT teams were putting up the police tape," Alaina Geary said.
When one of the suspects made his way into an apartment, police and neighbors feared that things could get worse.
"I'm thinking, 'I don't know what's going on,'" Jim Linehan said. "Just not respecting any sense or order. I'm quite concerned."
After the incident, Gross made sure everyone knew how dangerous of a job the officers responding in these situations have.
"From ambushes to the death of three officers, it’s now a very dangerous job," Gross said. "It is our job to patrol and protect the people of Boston, and unfortunately, some people take that out against us."