Two  massive explosions hits at the finish line of the Boston Marathon have resulted in injuries is it new al-qaeda attack.

Two explosions have been reported near the Boston Marathon finish line on Boylston Street as thousands of people gathered for the race, and there are reports of injuries.

Bloody spectators were being carried Monday to the medical tent that had been set up to care for fatigued runners. Police wove through competitors as they ran back toward the course.

“There are a lot of people down,” said one man, whose bib No. 17528 identified him as Frank Deruyter of North Carolina.

He was not injured, but marathon workers were carrying one woman, who did not appear to be a runner, to the medical area as blood gushed from her leg. A Boston police officer was wheeled from the course with a leg injury that was bleeding.

About three hours after the winners crossed the line, there was a loud explosion on the north side of Boylston Street, just before the photo bridge that marks the finish line.

Another explosion could be heard a few seconds later.

Race officials have locked down the hotel.

A photo has emerged which appeared to show the moment one of the blasts took place.

Police made their way through competitors as they ran towards the scene.

Bloody spectators were being carried to the medical tent that had been set up to care for tired runners.

“There are a lot of people down,” said one man, whose marathon number identified him as Frank Deruyter, who was not injured.

But marathon workers were carrying one woman, who did not appear to be a runner, to the medical area whose leg was hurt.

A Boston police officer was taken from the course with a bleeding leg injury.

Runner Laura McLean of Toronto said she heard two explosions outside the medical tent.

“There are people who are really, really bloody,” Ms McLean said. “They were pulling them into the medical tent.”

Cherie Falgoust was waiting for her husband, who was running the race.

“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.”