Justice Minister Antonis Roupakiotis said on Monday that authorities had been tipped off that crime boss Panayiotis Vlastos would try to escape from Trikala prison, central Greece.

Armed men attempted to help Vlastos break out from the jail on Sunday afternoon with the help of a helicopter. Prison guards exchanged fire with Vlastos’s accomplices, foiling the escape.

Some 500 shots were fired, forcing the helicopter to touch down outside the prison. Three armed men, a Greek, a Romanian and an Albanian, were arrested. They were armed with a Kalaskinov assault rifle and two Uzi submachine gun.

The helicopter’s pilot and engineer were also taken in for questioning.

Vlastos was injured during the escape. He climbed onto a rope ladder thrown from the helicopter but fell from a height of about 5 meters.

“We had information that there were some jails we needed to keep an eye on, including Trikala prison,” Roupakiotis told Mega TV on Monday.

Vlastos is serving a life sentence for his involvement in the so-called “crime syndicate,” which was responsible for a range of felonies, including blackmail, kidnapping and murder.

Vlastos attempted to escape from Korydallos prison in December 2011, when he took hostages, but he gave in.

Sunday’s attempted escape was the third time that a helicopter has been used in a prison breakout in Greece.

In 2006 and 2009, serial robber Vassilis Palaiocostas and his accomplice, contract killer Alket Rizai, successfully escaped from Korydallos prison in a helicopter.

Rizai was recaptured a few months later but Palaiocostas is still at large.