Militants behind an attack on Jordanian police supported Islamic State and investigations had revealed plans for more attacks on security and civilian targets, Jordan’s interior minister said on Monday.

Jordanian police said on Saturday a homemade explosive device planted near a police van killed a policeman and injured six others the day before.

The police vehicle had been maintaining security near a music festival in the majority Christian town of Fuhais, near the capital Amman and 15 kilometres (about 10 miles) from the hillside city of Salt.

In a huge security operation, Jordanian forces laid siege to a building in a residential part of Salt on Saturday night in search of those responsible for the bomb attack.

After the suspected militants refused to heed calls to surrender, the security forces stormed the building in a shoot out that resulted in the death of three militants and four security personnel, police said.

Ten members of the security forces were also injured.

Interior Minister Sameer al-Mobaideen said the militants, who blew up part of the building when the security forces stormed it, did not belong to a specific group but subscribed to Islamic State ideology.

Militants from Islamic State and other radical jihadist groups have long targeted U.S.-allied Jordan and dozens of militants are serving long prison terms.

“There were plots to wage a series of terror attacks that sought security points and popular gatherings. We know the targets but we won’t tell them so people won’t get terrified,” Mobaideen said.

King Abdullah, a Middle East ally of Western powers against Islamist militancy who has also safeguarded Jordan’s peace treaty with Israel, warned on Saturday the perpetrators of the attack would pay dearly.

SECRET INVESTIGATIONS

The monarch has been among the most vocal leaders in the region in warning of threats posed by radical groups.

The group were all Jordanian and there were no signs so far they had foreign links, Mobaideen said, refusing to give names of suspects. “The investigations are secret and ongoing,” he told a news conference

Alongside automatic weapons in the suspect’s possession, the authorities found a location where chemical ingredients for manufacturing explosives were buried, Mobaideen added.

General Hussein Hawatmeh, head of Jordan’ Gendarmerie, said the militant cell was recently set up and there were indications its members had embraced radical ideology.

“What is dangerous is that these new recruits are more impulsive than those with experience in executing operations that harm Jordan’s security,” Hawatmeh told reporters.

Jordan has been relatively unscathed by the uprisings, civil wars and Islamist militancy that have swept the Middle East since 2011.

But there have been some incidents of Islamist violence, increasingly carried out by members of powerful tribes that are traditionally the backbone of support for the ruling Hashemite dynasty.

Security forces have been extra vigilant having warned that sympathisers of Islamic State could launch revenge attacks after militants were driven out of most of the territory they once controlled in Syria and Iraq.

Intelligence officials and some experts believe widening social disparities and a perception of official corruption are fuelling a rise in radicalisation among disaffected youths in a country with high unemployment and growing poverty.

Blowback of Weapons Meant for Syrian Rebels Back into Jordan

Weapons shipped into Jordan for Syrian rebels by the Central Intelligence Agency and Saudi Arabia were stolen by Jordanian intelligence operatives and sold to arms merchants on the black market, the New York Times reported, citing American and Jordanian officials.

Some of the stolen weapons were used in a shooting in November that killed two Americans and three others at a police training facility in Amman, according to a joint investigation by the New York Times and Al Jazeera.

A Jordanian officer shot dead two U.S. government security contractors, a South African trainer and two Jordanians at a U.S.-funded police training facility near Amman before being killed in a shootout, Jordanian authorities had said in November.

The training facility was set up on the outskirts of the capital, Amman, after the 2003 U.S. invasion of Iraq to help rebuild the shattered country’s postwar security forces and to train Palestinian Authority police officers.

The weapons used in the shooting had originally arrived in Jordan for the Syrian rebel training program, the paper reported, citing American and Jordanian officials.

Theft of the weapons, which ended months ago after complaints by the American and Saudi governments, has led to a flood of new weapons available on the arms black market, the New York Times said.

Jordanian officers who were part of the plan “reaped a windfall” from sale of weapons, using the money to buy iPhones, SUVs and other luxury items, according to the paper, which cited Jordanian officials.