ANKARA (Reuters) - Turkish security forces launched an operation to hunt attackers near the Iranian frontier on Monday after one Turkish customs agent was killed when a rocket hit an armored bus carrying customs staff.

The rocket struck the vehicle’s front wheel around 0550 GMT on Monday, Interior Minister Suleyman Soylu said on Twitter. He said “the terrorists were followed and cornered”, but did not specify who the attackers were believed to be.

Turkish Trade Minister Rushar Pekcan said one of the customs agents was killed and several others wounded, including four in critical condition.

The office of the governor of Agri province said the vehicle was hit while in transit from the Dogubayazit area to a border gate at Gurbulak, causing it to skid off the road and flip over. It did not say who had carried out the attack.

The vehicle was near a parking lot for freight trucks some 3km (2 miles) from the border, hospital and security sources said. Ambulances, security forces and search and rescue teams were sent to the area.

Some Turkish media reports said the attack was carried out by Kurdistan Workers Party (PKK) militants, who have fought an insurgency against the Turkish state since 1984. The PKK are active in southeast Turkey but less so in Agri.

Television footage showed helicopters flying over the area after the attack, while Turkey’s state-owned Anadolu news agency said two combat helicopters had fired rounds on “areas where terrorists are believed to be”.

Anadolu said a soldier was critically wounded when an explosive was detonated during reconnaissance operations in the area.

Earlier this month, Turkey closed its land and air borders with Iran over an outbreak of the new coronavirus.