Twin suicide blasts in Aden killed six people and injured 31 others, according to two senior security officials in Yemen.
Two car bombers targeted the Aden counterterrorism headquarters building in the southern port city, the security officials said.
Most of the injured are being treated at nearby Jimhori Hospital, the officials said. Some are reportedly in critical condition.
ISIS claimed responsibility for the attack in a statement by its Amaq news agency. However, the group did not offer any evidence to support the claim.
CNN cannot independently verify that ISIS carried out the attack.
A large fire broke out in the counterterrorism headquarters and continued for at least an hour after the attack, one of the officials said. The building was seriously damaged, while nearby facilities and a hotel were also damaged from the attack, the officials said.
After the attack, road blocks were established on all main roads leading to the building and checkpoints were spread throughout the city.
Civil war has raged in Yemen for three years, during which the country has become the center of a proxy war between regional powers Iran and Saudi Arabia. Other non-state actors -- including ISIS, al Qaeda and Houthi rebels -- are also party to the conflict.
Yemen's internationally recognized government has made the city of Aden its base, but a southern separatist movement there threatens the fragile stability of the city.
Yemen is described by the United Nations as the world's worst humanitarian crisis. Over 10,000 people have been killed in the three years of war, an estimated 7 million are on the brink of famine, and 1 million people are threatened by an outbreak of cholera.