WASHINGTON — An American service member in Iraq was killed on Sunday by an improvised roadway bomb, the Pentagon said Monday.

A second service member was injured, the Defense Department said. Pentagon officials declined to release the identities of the victims or the location of the bombing, pending notification of family members.

Defense Department officials said that the two service members were involved in the fight against the Islamic State in Iraq. Since the war against the Islamic State began in 2014, 13 American service members have been killed in Iraq and Syria.