Emergency services at the scene of a shootout at the San Ysidro crossing
One of the busiest border crossings between the US and Mexico was closed for hours after a gun battle between US agents and suspected human traffickers.
Four people were injured at the San Ysidro crossing after the agents fired shots to stop three vans from storming across the border, US officials say.
Some 70 suspected illegal immigrants crammed into the vans were arrested.
The San Ysidro crossing is known as a major smuggling corridor for drugs and illegal immigrants.
US officials say the gun battle took place on Tuesday afternoon when the suspected human traffickers in three vans tried to storm past border agents at the congested crossing between the US city of San Diego and Mexico's Tijuana.
The agents then opened fire to stop the vans. However, some reports say the smugglers shot first at the agents - across lines of traffic at the crossing.
Three people in the vans and a motorist were injured, US officials say. The incident is being investigated by the San Diego police.
The northbound lanes were shut down for several hours, creating a massive traffic jam at the crossing.
Some 40,000 vehicles enter California every day at San Ysidro - one of the busiest ports of entry along the entire border between Mexico and the US.
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