At least 15 people have been killed in Yemen's coastal city of Aden, a local resident said, in an attack claimed by the local affiliate of the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group.

The resident, who wished to remain anonymous, told Al Jazeera that several people died in the city's Khormaksar district on Sunday after an explosives-rigged car blew up outside the criminal investigation department (CID) building.

Armed men, some of whom were wearing military fatigues, then proceeded to storm the facility where clashes were "still ongoing," the source said.

A separate source told Al Jazeera that at least "three terrorists" entered the CID building wearing suicide vests, but said there were no reports of hostages.

"No gunfire, no explosions, the situation is currently calm," the source said.

Also in Aden on Sunday, a car bomb targeted the Dar Saad-based office of Yemen's Islah (Congregation for Reform) party, the country's largest opposition group, the source said.

The building was abandoned and there were no reports casualties, the source said.

ISIL took responsibility for the attack on the CID building, according to its Amaq,website, claiming the armed group killed around 50 officers.

Al Jazeera could not independently verify the claims.

Earlier on Sunday, images posted on social media showed a pitched street battle between security personnel and unknown fighters near the CID building.

Video by Khaled Al-Senami of clashes between #Aden security forces and ISIS militants at CID HQ in Khormaksar filmed a few hours ago. #Yemen pic.twitter.com/XsxfqqHN9W — demolinari (@demolinari) November 5, 2017

Aden, the temporary base of Yemen's government, has seen a wave of bombings and shootings targeting officials and security forces in recent months.

Armed groups have gained ground in the south of the country since forces loyal to President Abd-Rabbu Mansour Hadi - backed by an Arab coalition assembled by Saudi Arabia - drove the Houthi fighters out of Aden in July last year.

Since then, the government and the Arab coalition have struggled to enforce their control as ISIL and al-Qaeda use the security vacuum to carry out attacks.

Sunday's violence comes a day after Houthi rebels claimed responsibility for a loud explosion in Riyadh, saying they fired a long-range ballistic missile that travelled more than 800km over the border with Saudi Arabia.

The war in Yemen, the Middle East's poorest country, started in 2014 after Houthi rebels seized control of the capital Sanaa and began pushing south towards the country's third-biggest city, Aden.

The Yemen government has been based in Aden and Saudi Arabia since 2014.

Concerned by the rise of the Houthi rebels, believed to be backed by regional rival Iran, Saudi Arabia and a coalition of Sunni Arab states launched an intervention in 2015 in the form of a massive air campaign aimed at reinstalling President Abd-Rabbu Mansour Hadi's government.

Since then, more than 10,000 people have been killed and at least 40,000 wounded, mostly from Saudi-led air raids.