Three masked men stole a massive block of gold worth more than $2 million from a Japanese museum in a heist police said Monday could have been prevented — if only the curators hadn't left its showcases wide open.

The Ohashi Collection Kan museum in Takayama, central Japan, had kept the 220-pound gold bullion unguarded by sensors or even a case because it wanted visitors to be able to touch it, according to local police officer Shinji Kurake.

But on Sunday, three men made off with the gold block in broad daylight, Kurake said. A female employee who was alerted by the sound of their footsteps tried to intervene but was roughly pushed aside.

"We were very shocked ... but of course this was a big block of gold, and there was no security," Kurake said. "I suppose they could have been a little more careful."

Police were still searching for the group, who were thought to be driven away by a fourth accomplice.

The Ohashi museum purchased the gold bar in 1994, according to its Web site. In today's gold prices, the block would be worth about $2.1 million.

The museum was closed for an "emergency holiday" on Monday and officials could not be reached for comment.