Amsterdam ? Thieves pried open the emergency door of a small Dutch museum with an iron bar and made off with six 17th- and 19th-century landscape paintings — the second major art heist in 10 days in the Netherlands.

The break-in at 3 a.m. Monday set off an alarm that summoned police within minutes but the burglars already had fled, leaving behind two paintings that they dropped in their haste and damaged, Mark de Kok, a spokesman for the city of IJsselstein, said Tuesday.

The paintings included three by Jan van Goyen, a prolific contemporary of Rembrandt who died in 1656. The others were a 17th century painting by Pieter de Neyn and 19th-century pieces by Willem Roelofs and Adrianus van Everdingen. The damaged works were by Salomon van Ruysdael and Salomon Rombouts.

The paintings, on loan from the Dutch government, were mostly river scenes set in the flat countryside typical of northern Holland, a specialty of the IJsselstein City Museum. The town is a suburb of Utrecht.

Police seized security cameras that may have captured the burglary on video, de Kok said. The museum will remain closed until Thursday while the investigation continues.

De Kok declined to put a value on the paintings, saying that could invite ransom demands from the burglars. But a Van Goyen was sold by Christie’s’ in London six months ago for more than $126,000.

The theft occurred 10 days after an armed robbery of two paintings by Salvador Dali and Tamara de Lempicka from the Scheringa Museum for Realism in Spanbroek, a small town in northwest Holland.

Security expert Ton Cremers said the two thefts were carried out differently, indicating no reason to connect them. The last major museum heist in the Netherlands was six years ago, he said.

“It’s just embarrassing,” said Cremers, of Museum Security Network, a private company that advises museums on security.

He said the thefts reflected poor security at smaller institutions, where alarm systems usually are inside display rooms rather than outside the building where thieves would first make contact.