Arsenal Street near the intersection of School Street is a four lane street that’s busy in the daytime and empty at night. There’s a Boston Sports Club and a Panera Bread, part of the Arsenal complex, on one side of the street, and a car wash on the other.
But by around 2 a.m. Friday, Arsenal Street was a parking lot full of dozens of police cars from several local departments, the FBI and The Bureau of Alcohol, Tobacco, Firearms and Explosives.
It had the look of a police state. Officers wearing bullet proof vests walked the streets. Police cars raced down side streets as the police radio crackled. At one point, two FBI agents holding papers walked hurriedly to the corner of School Street and Dexter Avenue. At around 3 a.m., a group of heavily armed SWAT officers emerged from the neighborhood. A Cambridge police bomb squad truck rolled up and went into the neighborhood.
Then, shortly after 3 am. police were seen searching through the Arsenal on the Charles office park. Officers clad in black and carrying automatic weapons walked up and down Arsenal Street and into the complex of offices. Police dogs could be heard barking from State Police cars nearby.
Deeper in the neighborhood, away from the sight of reporters gathered nearby, the heavily armed police were checking a 20-block area of the community, searching for one of the suspects in the deadly Boston Marathon terror bomb attacks. One suspect had already been killed in a shoot out with police. Police had followed the suspects to Watertown after the two men allegedly shot an MIT police officer in Cambridge.
The police were all business.
One man, who identified himself as a co-manager of a Newton restaurant, said he was driving to his home in the neighborhood shortly after midnight when, somehow, he got past the still-forming police perimeter and began driving toward a house that police apparently had surrounded.
The man, who asked that his name not be used, said agents in full-body armor, guns drawn, pulled him out of his car. “I got dragged out of my car with machine guns and everything,’’ he said, as he stood in the car wash parking lot in shirt sleeves, his abandoned car still parked a few blocks away.
By 2 a.m. or so, three or four reporters, photographers and videographers gathered near the Arsenal Street-School Street intersection. A police officer urged them to go across Arsenal Street, away from all the police activity, saying it wasn’t safe because they could be in the line of fire.
Vehicles headed west on Arsenal Street found a police barricade waiting at Arsenal Court.
"Ya gotta get outta here. There's an active shooter here with an active explosive. Go!" said an officer directing traffic.
Near the barricade, a group of curious bystanders gathered yards away from the traffic stop. Ambulances and fire trucks idled nearby.
Christie Rojas, 18, was walking with a friend down Arsenal St. at 3 a.m. hoping to find a gas station to buy cigarettes from when a police officer stopped her. “He told us to turn around because there’s a foot pursuit coming toward us,” she said.
Michael Demirdjian, 48, and his daughter Courtney, 17, had just picked up their new 8-month-old Alaskan Malamute, Hunter, from Logan Airport when they were stopped miles away from their Watertown home.
“I told them I needed to get the puppy home — he’s been cooped in a crate for 18 hours — but they wouldn’t let me in,” he said. “They told me to find another place to stay tonight.”
At 3:44 a.m., a SWAT officer approached Demirdjian and told him he would try to convince officials to get the family and dog home.
At the corner of Arsenal Street and School Street, Adonis Karageorgos, 35, a Tufts Dental School student, who said he came to the scene after nearing police cars race near his Watertown apartment on Coolidge Avenue racing toward Watertown Square a few hours earlier.
"I have never seen so many police descend so quickly. I think I counted 42 cop cars past my house," he recalled.
He heared a loud explosion as the police cars sped by.
"I saw it from my house and lit up the sky because it is overcast," he recalled.
He drove to Arsenal and School street to check out the scene.
Several blocks away, dozens of reporters and police set up a staging area in the parking lot of the old Watertown Mall, home to a Target store and Department of Motor Vehicles office. A few Target employees peered from inside their closed store.
At a briefing about 4:30 a.m., Boston Police Commissioner Edward F. Davis said the massive collection of federal, state, and municipal police were still searching for the surviving suspect.
“We believe this to be a terrorist,’’ Davis told reporters. “We believe this to be a man here to kill people.”
Andrew Ba Tran can be reached at Andrew.Tran@boston.com. David Dahl can be reached at email@example.com. Follow him on Twitter @globedavidd