Silva told the news outlet that he was near the finish line when the explosions happened. He said he saw a number of injuries in the area where spectators were. He saw "someone lost their leg," and he said "people are crying, people are confused."
"It was just an explosion, it came out of nowhere," he said. "There are multiple injuries. I saw dismemberment, I saw blood everywhere. People are badly injured."
[Update, 4:19 p.m. ET]
We have a new injury count: According to hospital officials, at least 28 people are being treated for injuries connected to this afternoon's blasts near the Boston Marathon finish line.
Nineteen were being treated at Massachusetts General and nine at Tufts Medical Center, officials at those facilities said. Boston police earlier put the number of victims at two dead and 22 hurt.
[Update, 4:16 p.m. ET]
"People started scrambling, pushing, shoving" when the explosions happened in a sidewalk area along Boylston Street, near the finish line in the Copley Square area, says CNN executive producer Matt Frucci at the scene.
Frucci said he heard the blasts.
"After the dust settled, (I saw) six or seven people strewn about the area where the second (explosion) was.
[Update, 4:11 p.m. ET]
A Red Cross website has been established to help people find loved ones in the area.
"Individuals can register themselves as safe or search for loved ones," Massachusetts' emergency management agency says.
[Update, 4:08 p.m. ET]
At least two people have been killed and 22 are injured in the apparent bombings near the finish line of the Boston Marathon, Boston police say.
[Update, 4:02 p.m. ET]
A Massachusetts General Hospital spokeswoman tells CNN 19 victims have been brought in.
[Update,3:57 p.m. ET]
On their Twitter page, Boston marathon officials made this announcement: "There were two bombs that exploded near the finish line in today's Boston Marathon. We are working with law enforcement to understand what exactly has happened."
[Update, 3:53 p.m. ET]
New York is taking precautions as a result of the explosions at the Boston Marathon.
In a written statement, New York Police Department Deputy Commissioner Paul Browne said: "We're stepping up security at hotels and other prominent locations in the city through deployment of the NYPD's critical response vehicles until more about the explosion is learned.
[Update, 3:45 p.m. ET]
Paramedics were treating several victims at the scene, and police ordered onlookers to back away from the area. Troops from the Massachusetts National Guard were assisting police as well.
Onlooker Josh Matthews said he heard the blast, then saw police running toward the scene.
"We just heard a lot of sirens, and people were kind of frantic, and it was a bad situation, so we got out of there," he said.
[Update, 3:37 p.m. ET]
Four victims of explosions near the Boston Marathon finish line are at the emergency room at Massachusetts General Hospital, a hospital spokeswoman told CNN. She had no information about the victims' conditions.
[Posted at 3:25 p.m. ET]
A pair of explosions rocked the finish line at the Boston Marathon on Monday afternoon, injuring at least a half-dozen people, a CNN producer at the scene said.
The blasts occurred a few seconds apart, shrouding downtown Boston's Copley Square in smoke. Paramedics were treating several victims at the scene, and police ordered onlookers to back away from the area, CNN Producer Matt Frucci reported.
The explosions occurred about 2:45 p.m., about an hour after the first runners had crossed the finish line, Frucci said.