The US has launched a worldwide investigation into the Boston marathon bombings. Two bombs, said to be pressure cookers packed with explosives and ball bearings, exploded near the finish line at around 12.20 am India time yesterday.

Officials said the devices were similar to those used against American troops in Iraq and Afghanistan and put the number of wounded at 176, many with critical injuries. President Barack Obama said, FBI is investigating it as an act of terrorism and it was not known if it was committed by an individual, a malevolent individual or an organisation, foreign or domestic.

Chief FBI investigator Richard DesLauriers said at a briefing that this will be a worldwide investigation and the agency will go to the ends of the earth to bring the culprits to justice.

Authorities searched the home of a Saudi national who is being treated at a Boston hospital for injuries suffered at the blast site. He has also been questioned. But police commissioner Ed Davis said the Saudi is not a suspect. The authorities insisted that there are no suspects or motives at present.

The blasts were the first terror attack on American soil since September 11, 2001, though there have been many on US facilities abroad, specially its diplomatic missions.