Five people including three soldiers were killed in a bombing targeting an elite army unit in the Philippines’s restive south, which Islamic State claimed was a suicide attack, authorities and experts said.

The military said the kidnap-for-ransom group and Isis-affiliate Abu Sayyaf was likely behind the midday blast on the island of Jolo on Friday, which also left nine other soldiers wounded.

Isis claimed the bombing was the work of two suicide attackers, according to tweets from Rita Katz, the director of SITE Intelligence Group which monitors jihadist activities worldwide.

The Philippines has renewed its campaign against the militants on Jolo this year after a suspected suicide bomber struck the island’s Roman Catholic cathedral in January, killing 21 people.

The country is home to numerous armed groups, several of which are linked to the decades-old insurgency aiming to create a Muslim homeland in the Christian-majority nation’s deep south.

Friday’s blast blew the roof off the sentry gate of the military camp and blackened its concrete walls, according to photographs of the aftermath of the attack shown on local television.

Three members of the military unit were killed and nine others were wounded, while two civilians – a motor tricycle driver and a woman street vendor – also died in the attack, army spokesman Colonel Ramon Zagala said.

“This attack is meant to disrupt the intensified security operations and our operational tempo following (a) series of recent operational gains in the area,” Zagala said in a separate statement.

The authorities could not say what kind of explosives were used.

Abu Sayyaf was active in the Philippines years before linking up with Isis, and has supported its violent activities with kidnapping.

The group has held hostages over the course of years and negotiated ransoms, but has also shown a willingness to kill its captivesj