(BOSTON) -- Police are ramping up security for Monday's Boston Marathon in the wake of last year's bombings.
Four-thousand police officers and 500 undercover plain-clothes detectives will be staged from the start line to the finish line.
Kurt Schwartz, Massachusetts' Undersecretary for Homeland Security and Emergency Management in the Executive Office of Public Safety and Security, said every section of the 26.2 mile race will be watched by cameras, which will be monitored in an underground, high-tech command center.
"A lot of eyes," Schwartz told ABC News. "They're all watching the public, watching the crowds, trying to detect suspicious behavior, trying to manage areas that just get too crowded… We have expanded across the board."
The command center will also be communicating in real-time with other offices across eight nearby cities and towns along the marathon path.
"We'll be looking for somebody who just doesn't feel right," Boston's new police commissioner Bill Evans said. "The characteristics – a lot of our officers, during their training, [are] looking at the characteristics of someone who might be carrying explosives."
Beyond just watching, Schwartz said security officials will be tailoring their tactical security on the ground throughout the day of the marathon based on what the surveillance cameras and officers on the scene are seeing.
Evans told ABC News that though security will be tight, it won't be overwhelming for runners or attendees.
"I don't want it to be an armed camp where people are going to be intimidated by the police presence," he said.
Evans' men got a trial run last week when an alleged hoaxer dropped two bags near the finish line of the marathon, in a similar manner to how the real explosives were planted last year. Authorities reacted quickly and destroyed the ultimately harmless objects.
"It was a nice drill," Evans said. "It just got us on our toes a little earlier… But I think we did a super job. We did what we were trained to do."
Authorities suspect last year's bombing was carried out by Tamerlan and Dzhokhar Tsarnaev, two brothers from Dagestan who lived in the U.S. Tamerlan was killed in a shootout with police days after the explosions. Dzhokhar was arrested and has pleaded not guilty to 30 counts related to the bombing. If convicted, he could face the death penalty.
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