A hydraulic jack used by thieves to enter the Sao Paulo Museum of Art remains in the museum's door Thursday in Sao Paulo, Brazil. Thieves broke into the museum Thursday and made off with Pablo Picasso's Portrait

Sao Paulo, Brazil ? Armed with nothing more than a crow bar and a car jack, it took thieves just three minutes to steal paintings by Pablo Picasso and Candido Portinari, worth millions of dollars, from Brazil’s premier modern art museum.

Authorities said they hit the Sao Paulo Museum of Art just before dawn Thursday – a time when the city’s busiest avenue is deserted and the guards inside were going through their shift change.

Jumping over a glass partition, they climbed an open concrete staircase leading up into the entrance of the two-story modernist building, which hovers over a large plaza on stilts of steel.

For a short time, they could have been seen from blocks away. But the thieves worked quickly. A few jabs of the crowbar, and they were able to slip a common car jack under the metal security gate. A few more cranks and they squeezed inside.

Hazy images from a security camera shows three men going in at 5:09 a.m. They smashed through two glass doors, ran to the museum’s top floor and grabbed the two framed paintings from different rooms, somehow avoiding nearby guards.

The alarm never rang, and by 5:12 a.m., they were making their escape.

“It was a professional job; it was something they studied because the paintings were in different rooms,” said the lead police investigator, Marcos Gomes de Moura.

Picasso painted “Portrait of Suzanne Bloch,” in 1904 during his Blue Period. It is among the most valuable pieces in the collection, museum spokesman Eduardo Cosomano said.

They also took “O Lavrador de Cafe” by Portinari, a major Brazilian artist.

“The prices paid for such works would be incalculable, enough to give you vertigo,” said curator Miriam Alzuri of the Bellas Artes Museum of Bilbao, Spain.

Jones Bergamin, a Sao Paulo gallery director, estimated the Picasso at about $50 million and the Portinari at $5 million to $6 million.

“I talked to friends at Christie’s and Sotheby’s and made the estimate based on the last Picasso that sold, ‘Garcon Avec Pipe,’ which is from the same blue period,” Bergamin said.

But Bergamin disagrees with the police theory that the thieves are professionals, because they ran past many other valuable paintings, including a very important Renoir, a Raphael, and paintings by Rembrandt and Degas.

“I think they took the Picasso because it was so small and the Portinari because it was hanging by the door,” he said.

The Picasso measures 26 by 21 inches and the Portinari 40 by 32 inches, the museum said.

Police believe that a fourth person may have acted as a lookout because they found headphones near the museum’s entrance.

Thieves attempted a robbery at the same museum in late October but were foiled by the alarm system. This time, the alarm failed. Moura said he believes Thursday’s robbery was carried out by the same gang.

Police were interviewing 30 museum employees, but none of the guards had fewer than 10 years on the job, Moura said. They also alerted Interpol and airport police to try to stop the paintings from leaving Brazil.

And while Moura doubts the paintings are being held for ransom, police are ruling nothing out. “Everything indicates they were sent to do it by some wealthy art lover for his own collection – someone who, although wealthy, was not rich enough to buy the paintings,” Moura said.