Malaysian police said that an attack at a bar last week, which injured eight people, was the first successful attack carried out by the Islamic State group — also known as ISIS — in the country. However, police had earlier said that business rivalry was a more likely motive for the June 28 grenade attack on the Movida bar and restaurant outside Kuala Lumpur.

The attack comes amid growing concerns in the country over ISIS-related attacks as a number of Malaysians have traveled to Syria to fight alongside the terrorist organization.

"There were elements of IS involvement in the attack," national police chief Khalid Abu Bakar told reporters. "We found out that the two of them received instructions from one of our own citizens in Syria ... to conduct attacks in Malaysia."

A total of 15 people have been arrested in wake of the attack, Bakar told CNN. That includes two policemen who have been arrested over suspicion of being involved in the attack.

"One of the policemen was picked up for harboring ISIS elements, while the other was arrested for involvement in robberies to collect funds for ISIS," he said.