Mexican authorities are searching for three thieves who walked into the federal mint's headquarters stole $2.5 million of gold coins from a vault Tuesday morning.

The trio of gunmen disarmed security guards at the Casa de Moneda de Mexico located in the center of Mexico City and escaped with 1,567 gold coins, commemorative watches and other valuables.

The value of the commemorative watches is unknown.

City Public Security Secretary Jesús Orta Martínez told reporters the suspects 'went straight to the vault, which was open' and they also 'breached three security measures.'

'The [first protocol breached was] that they very easily entered the building since it was not open yet. Second: they go to a vault that was open and at the end of the day that's what allows this to be done very easily and in a very short time,' the official said Wednesday morning.

He added authorities believe the men were still in Mexico City. Authorities said the suspects are between the ages of 25 to 30.

Authorities in Mexico are searching for three gunmen (one pictured) who raided the federal mint Tuesday and stole $2.5 million of old gold coins

Mexico's old 50-peso gold coins were first minted in 1921 to commemorate the first 100 years of independence (file image)

Mexico's federal mint was last robbed in July 2018 when at least four people took off with $153,000 worth of old silver and gold coins

Mexico's old 50-peso gold coins were first minted in 1921 to commemorate the first 100 years of independence and are now bought and sold by investors as their value fluctuates.

According to Mexican outlet La Vanguardia, the coins are estimated to have a pure gold content of 34 grams and a purity of 0.900.

Each century-old coin could sell over $1,910 on the open market.

Authorities said they have security footage showing the robbers.

One of the three accomplices is seen on the video wearing a camouflaged jacket and a dark colored hat. Another is wearing a collared shirt with a grey sweater over it and the third suspect has a grey sweatshirt and is carrying a backpack.

According to a police report, the men showed up at the mint at 9.30am local time.

The suspect who is seen on surveillance cameras wearing the shirt and sweater threatened one of the guards with his firearm.

Pictured are two of the three gunmen (left and right) who on Tuesday disarmed security guards at the Casa de Moneda de Mexico located in the center of Mexico City and walked out with rare gold coins that were first minted in 1921 to commemorate the first 100 years of independence

He and a second accomplice then entered the bank and cornered two employees and three women while the third suspect went inside the vault.

A fourth person remained outside as the lookout.

At about 9.40am, the three men exited the mint and sped off on a car.

Investigators with the Mexico City Attorney General's office questioned eight mint employees, including a 35-year-old security guard who was disarmed. Two of the employees reportedly broke company policy and took a meal break moments before the robbers arrived.

As part of the investigation, the security guards were stripped of their service weapon for not following protocols.

It's not the first time the federal mint has been targeted by armed thieves.

At least four men stole $153,000 of old silver and gold coins while the building was being renovated in July 2018.