Abraham Foxman. Photo: Justin Hoch.

The Anti-Defamation League (ADL), reacting to Monday’s Boston Marathon bombings that killed at least two people and injured more than 100, said it had already warned Jewish groups to be on alert this week due to the anniversary of the Oklahoma City bombing and Adolph Hitler’s birthday.

Federal authorities have classified the Boston Marathon bombings as a terrorist attack. A 20-year-old Saudi Arabian national is being held in custody as a suspect, the New York Post reported.

“It is sad that anytime a bomb explodes in public place we are conditioned as a first reflex to think of it as a terrorist attack; but unfortunately, in this instance it appears that our fears have been realized,” ADL National Director Abraham Foxman said in a statement.

“This apparent terrorist attack comes during a week when we are already on heightened alert because of the history of extremist-related events that have taken place during the week of April 20th, including the (April 19, 1995) Oklahoma City bombing and the federal raid of the Branch Davidian Compound in Waco, Texas,” he added.

Due to Hitler’s birthday of April 20, ADL had “issued a security alert to Jewish community institutions reminding them to be on high alert during this time of year,” Foxman explained.

The two bombs exploded near the finish line of the Boston Marathon among a crowd of runners and spectators. Kevin Goodman, 50, had just completed the race one hour before and felt the building of his hotel shake. “I was in the hotel recovering (from the race). I went outside to see the sights. It was gruesome. A lot of blood and limbs,” he told the Cleveland Jewish News.

“I knew they weren’t fireworks,” Goodman added. “I knew there was trouble. I can see the black plumes of smoke coming up to my room. I did go out and help until I was told to go back in (the hotel).”