Boston police at 1:02 p.m confirmed via Twitter that at least 22 are injured and are two dead following bomb explosions at the Boston Marathon on Monday.

Tufts Medical Center confirmed that nine victims have been taken there. Law enforcement authorities told ABC News they are testing smoke and materials found at the scene for chemical substances.

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The cause or source of the explosion has not been identified yet, however, thoughts of a terrorist attack have been circulating.

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Boston Police Department said two explosions took place on Boyleston street near the finish line of the Boston Marathon. The first runners in the marathon crossed the finish line around noon.Two explosions took place around 3 p.m., within second of each other.

TV helicopter footage showed blood staining the pavement around the marathon trail.

"There are people who are really, really bloody," said Laura McLean, a runner from Toronto treated in the medical tent for dehydration and then pulled out when room was needed for victims of the explosions. "They were pulling them into the medical tent."

The Associated Press spoke to Cherie Falgoust, who was waiting for her husband to finish the race when she saw the explosions.

"I was expecting my husband any minute," she said. "I don't know what this building is ... it just blew. Just a big bomb, a loud boom, and then glass everywhere. Something hit my head. I don't know what it was. I just ducked."