An attack on an Iranian police convoy in the country’s southern Sistan and Baluchestan province on Saturday killed at least 10 officers, authorities said.

Details remain limited about the attack in Gohar Kuh, about 1,200 kilometers (745 miles) southeast of the Iranian capital, Tehran.

Initially, reports simply described an attack by “bad guys” without further details. But shortly after, Iranian state media said 10 officers had been killed.

HalVash, an advocacy group for the Baloch people of Afghanistan, Iran and Pakistan, posted photos and videos of what appeared to be a disabled truck painted with a green stripe used by Iranian police vehicles. A graphic photo shared by the group showed what appeared to be the bodies of two police officers in the front seat of the truck.

HalVash said the attack appeared to target two security force vehicles and all those riding in them were killed. The truck appeared to have only bullet damage rather than any explosives used.

The state-run IRNA news agency said Eskandar Momeni, the country’s interior minister, had ordered an investigation into the incident, which it described as the cause of “the martyrdom of several policemen”.

Authorities have not identified any immediate suspects in the attack, and no group has claimed responsibility. The assault came after Israel launched a major attack in Iran early Saturday morning.

The Baloch regions of the three nations have faced a low-level insurgency by Baloch nationalists for more than two decades. Verification of information remains difficult in Iran’s Sistan and Baluchistan, which for decades has been the site of violence involving heroin traffickers.

The province is one of the least developed parts of Iran. Relations between the region’s predominantly Sunni Muslim residents and Iran’s Shiite theocracy have long been strained. Typical attacks involve hit-and-run attacks by militants in the region, such as the Sunni militant group Jaish al-Adl, killing several security officials at a time.

However, they did exist mass casualty attacks by the militants of the past. In April, gunmen wearing explosive vests attacked several places in the province, killing 10 before security forces shot dead 18 militants. Last December, another attack killed 11 and wounded eight others.

Meanwhile, the Taliban said they were investigating reports that Afghan migrants were killed by Iranian security forces in the region in early October, an incident that threatened to further strain relations between the nations.