US authorities announced that three people were killed and 27 others injured Sunday when a boat carrying migrants sank off the coast of San Diego, California, near the Mexican border.

Eyewitnesses documented the incident that occurred Sunday morning, in which the 12-meter-long boat appeared to slowly sink as it collided with the shore in rough seas, forcing its passengers to jump into the water to save their lives.

"It was a smuggling boat," Geoffrey Stephenson, a spokesperson for the US Customs and Border Guard Service, told reporters, indicating that it was apparently transporting undocumented immigrants to the United States.

He added that agents of the customs administration are currently questioning a man they believe is the captain of the boat.

The spokesman expressed his regret that "the smugglers do not care about the people who exploit them. All they care about is profit. The safety equipment was not enough and it is clear that the boat was very crowded."

Stevenson suggested that the survivors were immigrants who tried to enter the United States illegally.

The San Diego Fire Brigades Administration announced that the 27 survivors were taken to hospitals for treatment, noting that their wounds are of varying severity.

The United States is currently facing a massive influx of immigrants on its border with Mexico, where 172,000 people were arrested in March, the largest number in 15 years.