Johannesburg: Thieves reportedly using a vehicle with South African police markings staged a brazen heist at the main international airport in Johannesburg, officials and media said on Wednesday.

No shots were fired and no injuries were reported in the armed robbery, which occurred at around 7.45pm on Tuesday at O.R. Tambo International Airport, said Airports Company South Africa, which manages the facility. It was not known what if anything was taken, the company said in a statement. Some police officials have said the robbers stole an undisclosed amount of money.

Authorities were investigating the alleged use of a vehicle with police markings in the robbery, radio station Jacaranda FM quoted police Col. Athlenda Mathe as saying.

The Democratic Alliance, South Africa’s main opposition party, said it will ask a police watchdog agency to investigate whether police “members or assets” were used in the heist. It also said it will question the police and transport ministers about security at South African airports.

A company that tries to counter organised crime in the banking industry said it was deeply concerned by the boldness of the criminals as well as their ability to gain access to a secure area.

“It is evident that the heist was executed using accurate information,” the South African Banking Risk Information Centre said in a statement. “This incident exacerbates an already dire situation of attacks on cash in transit vehicles and staff.”

The group said it recorded 269 cash in transit “incidents” in 2016, although it did not say how many of those robbery attempts were successful. Some 57 incidents have been recorded so far this year, it said.

In 2006, thieves stole large amounts of cash from a plane at O.R. Tambo airport. Some gang members were later convicted.

South African police have periodically warned that some criminal gangs tail arriving travellers in vehicles from the Johannesburg airport and rob them on the road or when they reach their destination.