MEXICO CITY -- What started as an ambush quickly transformed into a manhunt on Wednesday afternoon, when police in Mexico's northern border state of Sonora repelled a highway attack, then chased injured shooters into the mountains nearby.

It was the second shootout in two days in a region where escalating clashes between authorities and powerful local gangs threaten to put a damper on the country's Day of the Dead celebrations.

Agents from the state attorney general's office were attacked while driving between the towns of Santa Ana and Magdalena de Kino, 56 miles (89 kilometres) from the Arizona border, authorities said in a post on Facebook. The attackers left three assault rifles, a truck and smears of blood before fleeing onto a mountain nearby.

Police officers and the military continue to search for the assailants.

Immediately following the attack, the mayor of Santa Ana evacuated the local school and postponed all Day of the Dead celebrations until further notice. The attack followed a more fatal confrontation in the neighbouring town of Altar on Tuesday morning, when gangs shot and injured at least four military personnel and a state police officer.

Initially Sonora's public security department took to X, the social media platform formerly known as Twitter, to report one member of the military had been shot dead, before hastily deleting the post.

Speaking to local reporters, Maria Dolores Del Rio, head of Sonora's security department, said the attack was a regrettable symptom of her office's crackdown on organized crime in the region. Altar, in particular, is a well known hub for migrant smuggling, often co-ordinated by local gangs.

Images of the Altar attack circulating on social media appear to show one completely burned military truck and another civilian truck peppered with bullet holes and spray-painted "vtasma," believed to be the call sign of a violent wing of the powerful Cazadores gang.

As tensions in the region rise, several other towns have cancelled their traditional Day of the Dead celebrations.

Benjamin Hill, a town 25 miles (40 kilometres) south of Santa Ana, cancelled a parade and altar-decorating ceremony on Tuesday afternoon, then called off all school buses heading north Wednesday. Next Santa Ana indefinitely postponed celebrations planned for this weekend. In Altar, celebrations are going ahead as planned.

--------

Follow AP's coverage of Latin America and the Caribbean at