A major port of entry in San Diego was closed for several hours on Sunday after a group of migrants on the Mexican side of the border rushed the area, leading US Border Patrol agents to fire tear gas at the group.

About 500 migrants overran Mexican police near the San Ysidro Port of Entry, two journalists at the scene told CNN. As the migrants tried to cross the border, agents on the US side deployed tear gas to disperse them. US Customs and Border Protection said migrants threw rocks at Border Patrol agents, prompting agents to respond with tear gas because of the risk to their safety. Mexican and US authorities said several people were arrested on suspicion of attempting to cross the border illegally.

The incident marked an escalation of tensions that have been mounting since groups of Central American migrants began arriving in the Mexican border city of Tijuana, drawing threats from US President Donald Trump to close the border. Meanwhile, Tijuana's mayor and city residents have been calling for the migrants' exit.

A migrant family from Honduras runs from tear gas that was deployed by US Border Patrol agents near the fence between Mexico and the United States.
A migrant family from Honduras runs from tear gas that was deployed by US Border Patrol agents near the fence between Mexico and the United States.
Kim Kyung-Hoon/REUTERS
Mexican police run as they try to keep migrants from getting past the border crossing in Tijuana.
Mexican police run as they try to keep migrants from getting past the border crossing in Tijuana.
Ramon Espinosa/AP
A group of migrants climbs the border fence between Mexico and the United States.
A group of migrants climbs the border fence between Mexico and the United States.
Pedro Pardo/AFP/Getty Images
Mexican police, right, stand guard as migrants walk on a bank of the nearly dry Tijuana River. The migrants were making their way toward the El Chaparral port of entry after circumventing a police blockade.
Mexican police, right, stand guard as migrants walk on a bank of the nearly dry Tijuana River. The migrants were making their way toward the El Chaparral port of entry after circumventing a police blockade.
Mario Tama/Getty Images
Migrants and journalists run away from tear gas.
Migrants and journalists run away from tear gas.
Alkis Konstantinidis/REUTERS
Migrants return to Mexico after tear gas was deployed.
Migrants return to Mexico after tear gas was deployed.
Adrees Larif/REUTERS
A migrant covers his face after being affected by tear gas.
A migrant covers his face after being affected by tear gas.
Adrees Latif/REUTERS
Migrants are stopped by Mexican police officers before arriving at the port of entry.
Migrants are stopped by Mexican police officers before arriving at the port of entry.
Pedro Pardo/AFP/Getty Images
A migrant climbs the fence between Mexico and the United States.
A migrant climbs the fence between Mexico and the United States.
Hannah McKay/REUTERS
A migrant is pushed back as she attempts to break through a line of Mexican police to reach the border wall.
A migrant is pushed back as she attempts to break through a line of Mexican police to reach the border wall.
Lucy Nicholson/REUTERS
A group of migrants crosses the riverbed of the Tijuana River in an attempt to get to the port of entry.
A group of migrants crosses the riverbed of the Tijuana River in an attempt to get to the port of entry.
Pedro Pardo/AFP/Getty Images
Migrants hold up their hands as US Border Patrol officers detain them. They had jumped over the border fence between Mexico and the United States.
Migrants hold up their hands as US Border Patrol officers detain them. They had jumped over the border fence between Mexico and the United States.
Jorge Duenes/REUTERS
US Border Patrol agents fire tear gas toward migrants at the border.
US Border Patrol agents fire tear gas toward migrants at the border.
Kim Kyung-Hoon/REUTERS
Migrants cross the Tijuana River to reach the border fence.
Migrants cross the Tijuana River to reach the border fence.
Kim Kyung-Hoon/REUTERS
Migrants climb a metal barrier on the border.
Migrants climb a metal barrier on the border.
Pedro Pardo/AFP/Getty Images
People attempting to cross into the United States gather near their vehicles after the San Ysidro Port of Entry was closed because of the migrant unrest.
People attempting to cross into the United States gather near their vehicles after the San Ysidro Port of Entry was closed because of the migrant unrest.
Mario Tama/Getty Images
A migrant is stopped by US agents who order him to go back to the Mexican side of the border.
A migrant is stopped by US agents who order him to go back to the Mexican side of the border.
Pedro Acosta/AP
Migrants are stopped by Mexican police officers.
Migrants are stopped by Mexican police officers.
Pedro Pardo/AFP/Getty Images
Migrants cross the riverbed of the Tijuana River as they try to get to the port of entry.
Migrants cross the riverbed of the Tijuana River as they try to get to the port of entry.
Pedro Pardo/AFP/Getty Images
Migrants clash with Mexican police.
Migrants clash with Mexican police.
Rodrigo Abd/AP
Migrants try to climb the border fence.
Migrants try to climb the border fence.
Pedro Pard/AFP/Getty Images