U.S. Secretary of State John Kerry on Thursday denounced the Boston Marathon bombings and pledged assistance to the family members of the foreign nationals killed or injured in the attacks.

"The entire State Department family joins President (Barack) Obama in offering our deepest condolences and sympathies to the families and loved ones of all those killed and injured in the April 15 attacks in Boston," Kerry said in a statement.

The secretary of state denounced the bombings in his home state as a "cowardly act of terrorism."

"It defies words to hear of children killed and horribly maimed on the streets of my city," Kerry said. "As secretary of state, I would underscore that this attack on America was also an attack on people everywhere, as the Boston Marathon has always been an international event that brings countries and peoples closer together."

Three people, including a Chinese graduate student, were killed and more than 170 others were injured in the twin blasts at the finish line of one of the world's most storied races.

"We share in the tragic loss of one young Chinese citizen killed that awful day, and all foreign nationals who have been injured," Kerry said.

He noted that State Department officials have been in contact with the Chinese victim's family in China, China's Ministry of Foreign Affairs and Chinese officials in the United States "to convey our condolences and offer our assistance."

"We stand ready to provide whatever appropriate assistance we can to the family members of foreign nationals in the aftermath of this despicable act of terror," Kerry said.