WASHINGTON
US President Barack Obama used the expression "act of terrorism" about Monday's blasts in Boston.
Obama said they did not know whether this act was planned or unplanned by a domestic or a foreign terrorist group or an individual act.
He called the bombing "a heinous and cowardly act" used to target innocent civilians.
FBI is investigating the incident as a "terrorist act", Obama told reporters on Tuesday.
When bombs are used to target innocent civilians, this is a terrorist act, said Obama, adding that they would find who was responsible for the attacks.
Two bombs went off near finish line at Boston marathon which was participated by nearly 23,000 people; and three people, including an 8-year-old child, were killed and over 170 people were wounded.
US President Obama to travel Boston on Thursday
Obama will travel to Boston on Thursday for a memorial.
Obama will attend the memorial service for the people who lost their lives in the explosion and deliver a speech there, said the White House statement.
It was added, Obama's April 19 event at the University of Kansas has been cancelled.
Two bombs went off near finish line at Boston marathon which was participated by nearly 23,000 people on Tuesday; and three people, including an 8-year-old child, were killed and over 170 people were wounded in US.
Turkey condemns deadly Boston Marathon bombings
The Turkish Ministry of Foreign Affairs on Wednesday strongly condemned the double bomb attacks on the Boston Marathon, which killed three people and wounded scores including children.
The ministry expressed deep sorrow over Monday's blasts, which US President Barack Obama said were investigated as "an act of terrorism."
"Turkey, together with its people and government, shares the sorrow of the Americans and offers condolences to the families and friends of the people who lost their lives," the ministry said.
