Rhino heads and horns were stolen from a National Museum of Ireland warehouse late on Wednesday night in Swords, Dublin.

The Irish Times reports on the theft which saw expensive rhinoceros heads and horns stolen.

During the burglary, a security guard at the warehouse was tied up by three masked men who remained in the warehouse stealing the goods for about an hour.

After the thieves left, the security guard freed himself and phoned authorities just after midnight.

A statement from Gardai said the burglars loaded the valuables into a large white van.

The statement also said, “A Garda investigation has begun into the theft. The value of the property stolen is estimated to be in the region of €500,000 ($652,000). The crime scene is sealed off for forensic technical examination and an incident room has been set up at Swords Garda station.”

The Irish Times goes on to report that in 2011, Europol identified an Irish organized crime gang as one of the most significant players in the illegal trade of rhino horns. The Irish gang, made up primarily of Irish Travellers, was thought to be responsible for rhino horn thefts in Italy, Germany and the UK.

The rhino horns are believed to be sold in the Chinese medicine market, or to an underground collectors’ market.