Police investigating the Boston marathon attacks urged the public Tuesday to come forward with any digital images they might have that could help solve the crime.

Speaking to reporters, Boston Police Commissioner Ed Davis appealed for "any photos that you have from around the time of the blast and particularly in that area" in the city center where Monday's deadly twin explosions took place.

"Photos taken close to the blasts, just before, just after... Those will be critical, and we'll prioritize those -- but give us the photos and as much information (as possible) that can help the investigators move forward."

Three people, including a child, were killed and more than 170 were injured in the explosions that occurred a few seconds apart near the finish line of the 117th rendition of the world's oldest international marathon.

Countless still and video images went up on social media such as Twitter and Facebook in the minutes and hours after the explosions.

Davis asked members of the public who submit images "to tell us what time those photos were taken" so that investigators don't have to lose time recovering electronic signatures from each and every image.

"Assistance from the public remains critical in establishing a timeline of events," added Richard DesLauriers, head of the Federal Bureau of Investigation (FBI) office in Boston.

EU, NATO react with horror at Boston attacks
Brussels (AFP) April 16, 2013 - EU and NATO leaders reacted with revulsion Tuesday to the twin bomb blasts at the Boston Marathon that killed at least three people.

"I condemn the appalling acts carried out in Boston and deeply regret the tragic outcome and loss of innocent lives. Those responsible for the atrocious acts will be brought to justice," said European Union President Herman Van Rompuy in a statement.

The attacks also wounded more than 100 and while President Barack Obama went on national television to guard against "jumping to conclusions," a senior White House official, speaking on condition of anonymity, said such an attack was "clearly an act of terror."

EU foreign affairs head Catherine Ashton said the attacks, "deliberately targeting men, women and children," were "reprehensible" and added: "We stand with the United States government and people in condemning this bombing."

European Parliament head Martin Schulz said "terrorism is never justified. We are with our American friends."

Meanwhile, NATO Secretary General Anders Fogh Rasmussen was also "deeply shocked."

"I express my heartfelt condolences to the families and loved ones of those who were killed, and I wish a full recovery to those who were injured. My thoughts are with the people of Boston and all of the United States."