Police showed up Tuesday on the Mexico City set of Alfonso Cuarón’s untitled period film after a group claiming to be local authorities assaulted and robbed members of the crew, according to a letter from the production obtained by Deadline.

Cuarón was not on the set at the time.

A view of the Mexico City skyline Wednesday June 30, 2004. Unusually windy weather and decades of anti-pollution measures created the cleanest smog-season air seen in Mexico City since officials started keeping records in the mid-1980s.(AP Photo/Jose Luis Magana)

“While members of our production team were working at the location of José María Iglesias Street in the Tabacalera community with official permits from the Film Commission of Mexico City, they were assaulted by workers of the Cuahutémoc District,” reads the letter, which was translated from Spanish. “It was not a ‘simple fight’ like the authorities have reported, it was assault and there were people injured: Two women were hit; five of our crew members were taken to the hospital; and phones, wallets and jewelry were stolen.

“After we filed the complaint, the response of the District was immediate and positive,” the letter from Espectáculos Fílmicos El Coyúl continues, “We hope that the district authorities will keep their promise and help compensate for the stolen items, as well as bringing those responsible to justice.” Read the full letter below.

According to Associated Press reports, municipal police said a group of people approached the crew on a downtown street and identified themselves as borough code inspectors. Police said that “after an exchange of words, there was an altercation.”

The untitled movie is Cuarón’s first to film in Mexico since 2001’s Y Tu Mamá También. The Oscar-winning Gravity filmmaker’s new pic chronicles a year in the life of a middle-class family in Mexico City in the early 1970s. Cuarón, Gabriela Rodriguez and Nicolás Celis are producing. Participant Media’s Jeff Skoll, David Linde and Jonathan King are executive producers.

Here is the translated letter from the production:

Yesterday, Tuesday, November 1, 2016, while members of our production team were working at the location of José María Iglesias Street in the Tabacalera community with official permits from the Film Commission of Mexico City, they were assaulted by workers of the Cuahutémoc District. It was not a “simple fight” like the authorities have reported, it was assault and there were people injured: two women were hit; five of our crew members were taken to the hospital; and phones, wallets and jewelry were stolen.

After we filed the complaint, the response of the District was immediate and positive. We hope that the district authorities will keep their promise and help compensate for the stolen items, as well as bringing those responsible to justice.

At the moment, we are not worried about our team’s safety. However, it is alarming that union workers from the Cuahutémoc District will attack and assault citizens that are legally doing their jobs.

We are very grateful to all the neighbors from José María Iglesias Street for giving us their support and help to the affected crew members.

Respectfully,

Espectáculos Fílmicos El Coyúl