Amsterdam, Netherlands ? Thieves Saturday broke into the Van Gogh Museum and made off with two works by the 19th-century master – less than a week after a multimillion-dollar gem heist from a Dutch diamond exhibition.

The value of the oils was not immediately known, but major works by Vincent Van Gogh sell for millions of dollars, art experts said.

The second-story job was the second theft from the museum in 10 years. Security had been boosted after the first robbery of the Amsterdam collection, which holds the world’s largest Van Gogh display – more than 200 paintings and hundreds of drawings.

“This is the worst thing that can happen to any museum,” said the director, John Leighton.

Alarms went off at 8 a.m., two hours before opening. By the time police arrived, the thieves had vanished, Leighton said.

Police were impressed. They had responded quickly and hoped to find the culprits still in the building.

Instead they discovered a 15-foot ladder leaning against the rear of the building. The thieves climbed to the second floor and broke a window, police spokeswoman Elly Florax said.

“View of the Sea at Scheveningen,” a small picture of a boat setting off into a stormy sea, was painted in two days in 1882. It is one of his first major pieces.

“Congregation Leaving the Reformed Church in Nuenen,” painted in 1884-85, shows the village church where Van Gogh’s father served as pastor.