Theft from Puerta de Alcalá art gallery happened overnight, with perpetrators apparently propping their haul against trees before loading it into a van

Police in Madrid are searching for about 70 paintings worth an estimated €600,000 (£475,000) after three men walked out of an art gallery with the works as the sun rose last Thursday.

The thieves are thought to have spent two to three hours carrying the paintings out of the Puerta de Alcalá art gallery and propping them against nearby trees before loading them into a van.

The men are believed to have entered by punching a hole in the wall of a neighbouring bar, said Pedro Márquez of the gallery, noting that the bar had been closed for about a year.

“Once the hole was made, one person entered the gallery, disabled the alarm and opened the doors.” From there, he added, “they were able to take out anything they wanted without any problems”.

Márquez said he was working to determine exactly how many paintings were stolen and their exact value. The thieves also made off with a receipt book from the gallery, and he worried they would attempt to pass off sales of the stolen artwork as legitimate.

Further details of the heist came from a security guard who was keeping watch at a nearby construction site.

After spotting the men carrying the paintings on to the street, the security guard stopped them to ask what they were doing. The men said they were from the gallery and were moving the paintings to be displayed somewhere else.

“At this time of night?” the security guard reportedly asked them. The men assured him that an early start was crucial to getting the paintings to their next destination in time.

The theft came as the gallery was preparing to host a solo show by Seville’s Pablo Segarra Chias. Márquez said the stolen works included 13 of Chias’s paintings, as well as work by Eustaquio Segrelles and Juan González Alacreu. “They took all our best work,” said Márquez.

While he had few hopes of recovering the pieces, Márquez said he was planning on posting pictures of the stolen artwork on the gallery’s website to at least prevent its sale on the black market. “This has destroyed us. It’s left us in a really tough situation,” he said. “Forty years of work and they just walked out with it.”