At least 15 people are missing after a speedboat capsized off the Chinese territory of Macau.
Macau officials said the boat was carrying migrants trying to enter the gambling hub illegally.
Four people managed to swim to safety and the boat has been recovered, but attempts to rescue others were hampered by strong tides.
Macau is a Special Administrative Region, meaning Chinese citizens wanting to visit need a permit.
But the BBC's Martin Patience in Beijing says it is common for people seeking work to cross the short distance from the mainland without official approval.