One man was shot dead and two others in the same vehicle were detained Sunday near the Shangri-La hotel in Singapore, where a security forum of regional defense ministers and military chiefs is under way.

All three are Singaporeans and no explosives, arms or weapons were found, the Singapore Police Force said in a statement on Sunday. A bag containing substances believed to be controlled drugs was recovered, the police said.

When asked at a police checkpoint to open the vehicle’s trunk, the 34-year-old driver accelerated, ignored warnings to stop, and crashed through barricades. Police then opened fire, according to an earlier statement.

Two passengers, 26 and 31 years old, have been arrested, the police said.

“Preliminary investigations indicate that this is an isolated incident,” according to the statement. Earlier, police closed roads temporarily and implemented security measures near the hotel, including vehicle and person check points.

U.S. Defense Secretary Ashton Carter and Chinese Admiral Sun Jianguo are among those attending the Shangri-La conference, where territorial spats in the South China Sea and East China Sea often loom large. Carter called for China and its neighbors to agree on a long-delayed code of conduct for the waters before year’s end, and Sun focused the bulk of his speech on setting out China’s collaboration in the region.

The driver and one of the passengers were wanted by the authorities for various offenses.