A collision between a U.S. Customs and Border Protection (CBP) boat and a small vessel on Thursday led to the death of a woman who was traveling on the panga motorboat, which authorities believed was being used to try to smuggle immigrants into the United States, Fox News reported.

The incident occurred in the predawn hours off the coast of Encinitas, California -- a city about 22 miles north of San Diego -- when authorities spotted the suspicious vessel, which they said was crowded with 20 individuals assumed to be trying to enter the country illegally.

Federal agents first ordered the skipper of the 26-foot-long boat to stop and then fired warning shots when it continued on its course, the news channel detailed. Eventually, the two vessels collided, which led to the panga capsizing and its occupants being thrown into the water.

When the agents pulled the passengers from the water, they discovered that one woman was unconscious, the Associated Press noted. A U.S. Coast Guard helicopter took the injured woman to a local hospital, where she was pronounced dead, a dispatcher with the Coast Guard told the newswire.

The Mexican government confirmed late Thursday that the deceased woman was a Mexican citizen, Fox News said; a statement from the country's Foreign Relations Department noted further that another national was seriously injured, while two others suffered less severe injuries.

According to the Border Patrol, the 19 survivors were taken into custody by officials who met the Customs boat, the Los Angeles Times noted. Four of them needed to be hospitalized, the agency told the newspaper.

CBP spokeswoman Jackie Wasiluk, meanwhile, told Fox News that it was not clear whether the pilots of the panga were transporting any other contraband.

A Border Patrol boat was checking the waters around the interception site to see if any other cargo items, such as drugs, had been tossed off board, officials told the Los Angeles Times. CBP and the Border Patrol also noted that a thorough investigation of the incident was ongoing, the newspaper added.