The Fighter actor is producing and starring in Patriots Day, a film chronicling the events surrounding the attacks, which cost three people their lives and left 264 others injured, many seriously.

Mark, a Boston native, will play a Boston Police Sergeant who is central to the investigation and subsequent manhunt for brothers Dzhokhar and Tamerlan Tsarnaev, who planned the bombings.

Three years after the incident, Mark was on the same marathon course and just steps away from where the explosions were set off as he filmed scenes near the finish line.

Mark was photographed in a police uniform as he hit the streets with cameramen following closely behind him, and he reportedly filmed other scenes along the rest of the route while the 2016 marathon took place. The movie star has been in Massachusetts filming the movie for the past few weeks, and on Saturday (16Apr16), he took a break to visit a group of runners from Spaulding Rehabilitation Hospital, who competed in the marathon on Monday.

During the visit, he admitted he was initially reluctant to take on the project, but the "powerful and inspiring" script ultimately changed his mind.

He told the runners, "I can guarantee every one of you guys that we are going to make every single person very, very proud, and that's what we're committed to doing. I want to promise you guys how committed I am, how committed we all are, to getting it right and making everybody proud."

Patriots Day also stars John Goodman, Michelle Monaghan, J.K. Simmons, and Kevin Bacon, and is set for a U.S. release in December (16).