A woman was killed Thursday when a boat carrying 20 Mexican migrants collided with a US border patrol vessel off the California coast, authorities said.
The Mexican government called for an investigation into the incident, in which four people were also injured.
According to a statement from the US Customs and Border Protection (CBP) agency, a patrol boat had spotted a suspected human smuggling vessel off Encinitas in southern California.
US agents ordered the boat to stop, but it failed to do so.
"After failing to yield, warning shots were fired," the CBP said in a statement.
"After the suspected smuggling vessel failed to comply, the two vessels collided. The smuggler's vessel capsized, resulting in 20 people going into the water."
US agents pulled everyone out of the water but one woman was unresponsive and was later pronounced dead.
Of the 19 survivors, four were taken to the hospital with non-life threatening injuries.
All 20 people were suspected of attempting to enter the United States illegally.
Smugglers frequently try to circumvent the heavily patrolled land border between the United States and Mexico by using small boats to travel up the California coast.