CAMBRIDGE, Mass. -- It's about 9:50 a.m. Friday when three police vehicles loaded with law enforcement officials tear through the intersection of Vassar and Main streets on the MIT campus.
You hear them before you see them, and because the streets in this part of Cambridge, not far from the Charles River, are pretty much deserted, they can travel mostly unimpeded.
They roar past a television reporter doing a stand-up outside the Stata Center, a massive academic facility at MIT marked by its distinctive architectural design. It was near the Stata Center on Thursday night where the two suspects in the Boston Marathon bombings are believed to have shot and killed an MIT police officer after attempting to rob a nearby convenience store.
Authorities identified the officer as Sean Collier. He was 26.
A few yards from the stylized MIT/Stata Center sign that denotes the complex, someone had placed an American flag on a small pole in the earth. It flapped in the breeze.
In Kendall Square, normally abuzz with people either coming from the subway system, the nearby MIT campus or the Marriott hotel that sits at the edge of campus, the benches were for the most part empty. A group of law enforcement officers, many wearing body armor, stood watch near the entrances to the subway, whose large iron gates were closed as the area's massive transit system was shut down during the ongoing hunt for the second bombing suspect.
A woman delivered a tray full of coffees to the officers. She is told the gesture is a thoughtful one, but she points out that the officers are the ones who should be congratulated.
With the region on lockdown, a ban on cab use and widespread business closures, there is an eerie stillness.
A man on a skateboard, a jogger or two, some workers having a cigarette outside one of the campus buildings are the exceptions to the rule on this day, not the norm.
At the corner of Portland and Broadway, a Cambridge Police SUV races, lights flashing, in the opposite direction, toward the earlier convoy of police vehicles. It is followed by an MIT police vehicle. Back on Main Street, another police vehicle makes a sharp turn and speeds away with lights activated.
In the distance, more sirens.
On a normal day, you wonder how often these sights or sounds pass without notice, how often their comings and goings are simply part of the background of ordinary life.
Today, every movement takes on a more urgent, even ominous tone as the manhunt intensifies.
At the Marriott, police personnel occasionally enter the hotel to use the facilities. Guests ask if they can take a picture with the officers, whose garb identifies them as military police. The officers are gracious and pose with the group.
Hotel officials stop people as they enter the building to ensure they are registered guests. On the other side of the Marriott, a flag outside the John A. Volpe National Transportation Systems Center flies at half-staff.
Outside, a police officer approaches a reporter to check identification.
"Would you stay inside for the rest of the day until we catch this guy?" he asks.