SANAA - At least one person was killed and 17 wounded Wednesday when a car bomb struck the residence of Iran’s ambassador in Yemen, where Tehran is accused of backing Shia militia.

Ambassador Hassan Sayed Nam was not at home when the attack took place in the diplomatic district of Hada in the capital Sanaa, according to a security official.

The son of a guard at the residence was killed, according to an interior ministry statement given by the official Saba news agency. A security official had earlier said it was a guard who died. Two of the 17 wounded were guards and the rest passers-by, officials said. The blast left a hole in the outer wall of the house. Nearby homes and cars were also damaged. The identity of the attackers was unclear and the interior ministry said it had launched an investigation into the attack.

Huthi militiamen who have overrun the capital quickly cordoned off the area, which is near the intelligence headquarters in Sanaa, according to residents. It was not the first attack targeting Iran in Yemen.  On January 18, Iranian diplomat Ali Asghar Assadi was fatally wounded in a drive-by shooting outside the ambassador’s residence in what Tehran said was a kidnap attempt. Al-Qaeda Sunni extremists are still holding embassy staffer Nour-Ahmad Nikbakht who was abducted in July last year. Iran’s Deputy Foreign Minister Hossein Amir-Abdollahian told the Arabic-language Al-Alam television channel that “no Iranian diplomat was wounded” in Wednesday’s attack.

Violence has increased in Yemen since Huthi militia, also known as Ansarullah, swept into Sanaa in September.

The Huthis are accused of receiving backing from Shia-dominated Iran.

Their attempt to advance in regions south of Sanaa has been met by deadly resistance from Al-Qaeda insurgents who are active in the country, as well as tribes in central Yemen.

President Abdrabuh Mansur Hadi has decried “foreign plots” that he says are aimed at blocking progress in the impoverished country.

In September Hadi, a Sunni originally from the south, urged Iran to be “reasonable” in dealing with Yemen. He said “internal and foreign forces” had allied to disrupt the political transition following a 2011 uprising that ousted veteran president Ali Abdullah Saleh.

In September Yemen reportedly freed two Iranians said to be members of Iran’s elite Revolutionary Guards who were accused of having trained the Shia militia fighters.

Al-Qaeda’s leader in Yemen last month accused the Huthis of collaborating with the United States and Iran to try to “destroy” Sunni Muslims.

Last month, Al-Qaeda’s media branch claimed on Twitter that its fighters set off explosive devices at an entrance to the US embassy in Sanaa, according to the SITE Intelligence Group.

There has been no confirmation by US authorities of such an attack.

Washington regards Al-Qaeda’s Yemen-based affiliate as its most dangerous and has been waging a drone war against its leaders for years, with the backing of first Saleh and more recently Hadi.