THE HAGUE, Netherlands (AP) — Thieves blew open the door of an art gallery in the southern Netherlands and stole two works from a famous series of screen prints by American pop artist Andy Warhol and left two more badly damaged in the street as they fled the scene of the botched heist, the gallery owner said Friday.

Mark Peet Visser said the thieves attempted to steal all four works from a 1985 Warhol series called “Reigning Queens,” which features portraits of the then-queens of the United Kingdom, the Netherlands, Denmark and Swaziland, a small landlocked kingdom in southern Africa which is now called Eswatini.

In a telephone interview, Visser said the heist early Friday at MPV Gallery in the town of Oisterwijk was captured on security cameras, and called it “amateurish.”

“The bomb attack was so violent that my entire building was destroyed” and nearby stores were also damaged, he said. “So they did that part of it well, too well actually. And then they ran to the car with the artworks and it turns out that they won’t fit in the car. ... At that moment the works are ripped out of the frames and you also know that they are damaged beyond repair, because it is impossible to get them out undamaged.”

Visser declined to put a value on the four signed and numbered works, which he had planned to offer for sale as a set at an art fair in Amsterdam later this month.

The thieves got away with portraits of Elizabeth II of the United Kingdom and Margrethe II of Denmark. The prints of Queen Beatrix of the Netherlands and Ntombi Tfwala, who is now known as the queen mother of Eswatini, were left on the street as the thieves fled, Visser said.

Police appealed for witnesses as forensic experts examined the badly damaged gallery on Friday.