国际英语新闻:Obama says FBI investigating Boston explosions as "act of terrorism"

WASHINGTON, April 16 (Xinhua)-- U.S. President Barack Obama said on Tuesday the FBI was investigating Monday's explosions at Boston Marathon finish line as "an act of terrorism."

Speaking at the second televised statement following Boston explosions, Obama called the explosions, which killed three and injured more than 100, "a heinous and cowardly act."

"And given what we now know about what took place, the FBI is investigating it as an act of terrorism," said Obama, "Any time bombs are used to target innocent civilians, it is an act of terror."

Obama said the authorities still did not know "who carried out this attack or why, whether it was planned and executed by a terrorist organization, foreign or domestic, or was the act of a malevolent individual."

But he vowed again that the government will "find whoever harmed our citizens" and "will bring them to justice."

Obama said the federal government will continue to mobilize and deploy all appropriate law enforcement resources to the investigation and response work.

U.S. Defense Secretary Chuck Hagel Tuesday called the deadly bombings at Boston Marathon a "cruel act of terror," while saying it was important not to jump to conclusions before having all the facts.

The twin bombs exploded at around 3 p.m. local time (1900 GMT) Monday within seconds of each other near the finish line of one of the world's most revered races. The authorities said the bombings left three dead and injured over 140. Yet U.S. media reported the casualties had soared to 176.