Police in Singapore stepped up security around the venue of a major international conference Sunday after officers fatally shot one man and detained two others at a nearby roadblock.

The Shangi-La Dialogue security conference, a major event in the Asia-Pacific region attended by U.S. Secretary of Defense Ash Carter and delegates from dozens of countries from around the world, was uninterrupted but access to the venue was restricted.

Police said in a statement Sunday that officers opened fire after a vehicle with three people aboard crashed through police barricades. Substances believed to be drugs were found on one of the two people detained. The third man was shot dead, police said.

Security around the conference venue was increased and traffic rerouted. Police said they were in control of the situation.