Tijuana, Mexico (CNN) A major US-Mexico border crossing in San Diego was closed for hours on Sunday after a group of migrants on the Mexican side rushed the border area, leading US Border Patrol agents to fire tear gas at the group.

About 500 migrants on the Mexican side of the border overwhelmed police blockades near the San Ysidro Port of Entry Sunday afternoon, two journalists at the scene in Tijuana told CNN.

A migrant family runs from tear gas released by US border patrol agents near the fence between Tijuana, Mexico, and San Diego.

As the migrants tried to cross the border, authorities on the US side used tear gas to disperse them, the journalists said. Video of the scene showed a cloud of tear gas that sent people running and screaming, including families with young children.

US Customs and Border Protection said the migrants threw projectiles that struck several agents.

"Border Patrol agents deployed tear gas to dispel the group because of the risk to agents' safety," the agency said on Twitter.

Read More