A suicide bomber in a car targeted a convoy of vehicles carrying foreign forces in the Afghan capital, Kabul, on Thursday, May 16, Reuters reported citing Kabul Police Chief Ayoub Salangi.

Salangi said he feared there were casualties from the attack, which took place in the industrial zone of Kabul at around 8 am (11.30 pm EDt Wednesday). Sirens could be heard after the attack.

"A suicide bomber driving a (Toyota) Corolla targeted a convoy of foreign troops," he said.

NATO's International Security Assistance Force said it was aware of an explosion in Kabul, and was looking into reports of ISAF casualties.

The National Directorate of Security, Afghanistan's intelligence agency, says it thwarts a large number of attacks on the capital on a weekly basis.

The last suicide bomb attack in Kabul was in March, when a man blew himself up at a Defense Ministry gate, killing nine Afghans, during a visit by U.S. Defense Secretary Chuck Hagel.