A police officer has been arrested and is under investigation after at least one student was injured in gunfire at a demonstration outside a university in Mexico City. The shooting — in which two people received wounds, according to local reports — occurred when the lawman opened fired on a crowd that had gathered to organize a Nov. 20 national strike to demand justice for 43 students who disappeared after authorities open fired on them during a protest in September, according to local reports.

A group from the National Autonomous University of Mexico (UNAM) was standing near the Che Guevara Auditorium — a historic stronghold for social movements — to discuss their participation in an upcoming action when they were fired upon, Latin American news agency Telesur reported. The officer said he fired his gun in the air in a bid to deter around 20 people, and a bullet struck a male student in the thigh, according to a statement from city prosecutors.

The national strike has been called for in protest to the presumed killing of dozens of students from the Ayotzinapa teachers training college in Guerrero state — which classmates blamed on a corrupt local government and a police force with close ties to drug cartels.

Saturday's clash at UNAM began when a car marked as law enforcement pulled up near a group of students standing outside the Che Guevara Auditorium — a building on campus that has been occupied by leftist students after a police crackdown on a student strike in 1999. The Associated Press reported that the officer and three officials from the city’s prosecutor’s office where there to investigate a student’s complaint of a cellphone theft earlier this month.

UNAM students said one of the men began taking photographs of them. The students confronted the men — who were reportedly wearing official badges and weapons, photos of which were posted online, which confirmed his position with the local police force.

Students said the men reacted aggressively, and soon after violence broke out. Authorities claim the officers were verbally and physically assaulted prior to the shooting, with a group surrounded their car and throwing rocks, according to the Attorney General of the Federal District of Mexico City (PGJDF).

Sources from the Federal District told local reporters that two people were wounded from one bullet after the shooting. The officer who fired has been arrested, according to the PGJDF.

UNAM students called the shooting a "clear provocation meant to plant panic among the public to demobilize the thousands who have gone to the streets demanding justice for the disappearance of the 43 (Ayotzinapa students)," in a statement on Saturday.

The Inter-university General Assembly, an umbrella group for Mexican university students, called on UNAM officials to speak out against the shooting and called the incident another example of state repression of social movements, according to Sin Embargo, a Mexican news website.

Tension has been high between student activist groups and a police force perceived as corrupt and responsible for a series of needless shootings, the most recent of them the incident that preceded the disappearance of the 43 students in Guerrero state.

Students from Ayotzinapa, a college that caters to the rural poor, had been protesting government education reforms they said would make school unaffordable for the poor when police opened fire on them.

After that shooting, which left six people dead, dozens of local police were arrested and a warrant was issued for the arrest of the local mayor after a series of confessions from drug cartel members implicated both in the student's disappearance.

Iguala mayor Jose Luis Abarca, who went into hiding along with his wife after the students' disappearance, was apprehended earlier this month in Mexico City by federal police. Last week, gang members confessed to the mass killing of the students, describing the crime in detail, but their bodies have not been found.

The close ties between local government, police forces, and drug cartels revealed in the aftermath of the students' disappearance has seemingly undermined President Enrique Pena Nieto’s claims that Mexico has become safer on his watch. About 100,000 Mexicans have been killed since 2006 when the government went to war against narco crime organizations.