(Photo Credit: U.S. Coast Guard photo by Petty Officer 3rd Class Andrew Barresi)

The runners competing in today’s Boston Marathon might have spotted a Belgian Malinois on the sidelines of the race track, or a German Shepherd by the waterfront. These dogs were members of the Coast Guard K-9 unit from Maritime Safety and Security Team New York, and they made sure runners stayed safe every step of the way.

Rruthie is a three-year-old Belgian Malinois trained to sniff out explosives. On the Sunday before the big race, she and her handler Petty Officer 3rd Class Richard Barone patrolled the race track and sniffed the area by the waterfront. The partners were brought in from New York to help Maritime Safety and Security Team Boston secure the event and prevent any attempt at violence.

The Coast Guard maintained a visible security presence throughout the race.

“Our presence alone can act as a deterrence for someone planning to do harm,” Barone said.

Security at the race has become a top priority since the devastating Boston Marathon bombing in 2013. Two pressure cooker bombs killed 3 people and injured 264 others. Dzhokhar Tsarnaev, the only surviving perpetrator of the terrorist attack, was recently sentenced to death for his crimes. His accomplice and brother, Tamerlan Tsarnaev, who was shot by police a few days after the bombing.

About 30,000 people participated in Boston Marathon 2016.