SAÕ PAULO, Brazil - With nothing more than a crowbar 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 the thieves hit the Saõ Paulo Museum of Art just before dawn yesterday, when the city's busiest avenue was deserted, and the guards inside were changing shifts.

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

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 show three men going in at 5:09 a.m. They smashed through two glass doors, ran to the top floor, and grabbed the two framed paintings, 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. It was painted in 1939 and depicts a coffee picker.

"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 Saõ Paulo gallery director, estimated the Picasso's worth at $50 million and the Portinari's at $5 million to $6 million.

But Bergamin disagreed with the police theory that the thieves were professionals, since they ran past many other valuable paintings.

"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.

Thieves tried to rob the same museum in late October but were foiled by the alarm system. This time, the alarm failed. Moura said he believed yesterday's robbery was carried out by the same gang.