Two Saudi nationals were injured in the bombings in Boston but neither is accused of involvement even though one was initially put under armed guard at a hospital, the embassy said Tuesday.

The Saudi embassy in Washington said that two of its nationals, one man and one woman, were wounded in Monday's blasts. Police earlier said that the 20-year-old man was being guarded but was not under detention.

The explosives used in the Boston Marathon bombings were likely homemade devices full of nails and metal fragments designed to cause widespread injury, according to initial reports.

A day after an attack that left three dead and more than 170 wounded, the FBI and Boston police declined to reveal details of their probe, or whether they suspected the assault was linked to foreign or domestic extremists.

Iran's foreign ministry strongly condemned the twin bomb blasts at the Boston Marathon that killed at least three people, the country's state television reported on Tuesday.

"Iran strongly condemns the killing of American citizens in Boston," said ministry spokesman Ramin Mehmanparast, calling the bombings a "source of sorrow".

U.S. Ambassador to Lebanon Maura Connelly conveyed on Tuesday U.S. condolences for the recent deaths and injuries of Lebanese nationals from attacks originating from inside Syria that have struck Lebanese villages.

She reiterated after holding talks with caretaker Prime Minister Najib Miqati “the U.S. call on all parties in the region to avoid any actions that would exacerbate the crisis in Syria, increase the propensity for spillover violence, and negatively impact civilian populations.”

The Pakistani Taliban, which claimed the 2010 Times Square bomb plot, on Tuesday denied anything to do with explosions that killed three people in Boston.

"We believe in attacking U.S. and its allies but we are not involved in this attack," Tehreek-e-Taliban Pakistan (TTP) spokesman Ehsanullah Ehsan told Agence France Presse.

The twin blasts that killed three people and injured scores at the Boston marathon are a warning for Russia as it prepares to host the 2014 Winter Olympic Games, the sports minister said on Tuesday.

"For Russia, which will have to soon stage a number of major sporting events, this is a serious warning bell," RIA Novosti quoted Vitaly Mutko as saying.

The head of an extremist Jordanian Muslim Salafist group said early Tuesday that he was "happy to see the horror in America" after the explosions in Boston.

"American blood isn't more precious than Muslim blood," said Mohammad al-Chalabi, who was convicted in an al-Qaida-linked plot to attack U.S. and other Western diplomatic missions in Jordan in 2003.

The northeast of the United States crawled out from under a mammoth blizzard Sunday that caused at least nine deaths and paralyzed the region with high winds and heaps of snow.

More than 300,000 customers were still without power in the wake of the storm that struck a slew of states and dumped as much as three feet of snow across New England before battering three Canadian provinces.

Flights resumed with delays at New York airports Saturday after a fierce blizzard passed.

"Airlines are expected to begin limited service this morning, but all travelers should check with airlines carriers for flight status," the New York and New Jersey Port Authority said on Twitter.

The next time your car hits a pothole, a new technology could help you immediately tell someone who can do something about it.

Boston officials are testing an app called Street Bump that allows drivers to automatically report the road hazards to the city as soon as they hear that unfortunate "thud," with their smartphones doing all the work.