A helicopter has swooped on a prison courtyard as armed men on board fired at guards and lowered a rope to help a convicted killer make his fourth attempt to escape from a Greek prison.
But the plot was foiled when the prisoner was shot and the helicopter was forced to land in the prison's car park.
Authorities say the chartered helicopter - carrying two armed passengers, a pilot and a technician - first tried to rip off the chicken-wire fence surrounding Trikala prison with a hook dangling from a rope.
When that didn't work, a rope was lowered to whisk away Panagiotis Vlastos, a convicted murderer and racketeer.
Another prisoner, an unnamed Albanian national also in the courtyard at the time, may have been part of the escape plan.
The armed passengers used AK-47 assault rifles to fire on the prison guards. One guard, who was inside a post, was slightly injured by shards of flying glass.
He and others returned fire, injuring Vlastos, who had managed to climb into the helicopter, as well as the helicopter's technician.
Vlastos fell from about three metres into the courtyard and the helicopter was eventually grounded in the car park.
Vlastos, 43, who is serving a life sentence had tried and failed three times before to escape from jail. Prison officials told TV stations Mega and NET they recovered more than 500 bullets fired from the helicopter.
The Greek Ministry of Justice said the helicopter passengers also carried "improvised explosive devices" but did not use them.
Authorities said Vlastos was wounded in the legs and was being treated in the prison hospital.
The technician suffered a minor hand injury.
It was not immediately clear if the pilot and flight technician had willingly taken part in the escape attempt or had been forced to fly to the prison, 330 kilometres north-west of Athens.
It was also unclear whether the second would-be escapee was part of the scheme or just happened to be in the courtyard and tried to take advantage of the situation.
The helicopter was hired from a western Athens suburb and was supposed to fly to Thessaloniki, in northern Greece.
However, it deviated from its flight path to head to the prison.
This is the third time a helicopter has been used in an attempted prison escape in Greece.
Convicted criminals Vassilis Paleokostas and Alket Rizaj were whisked by helicopter from the high-security Korydallos prison in Athens in June 2006.
They were caught but escaped for a second time - again using a helicopter - in February 2009. Paleokostas is still at large.
Vlastos was first arrested in 1994 over the murder of two members of a rival criminal gang.
He was convicted last year as the behind-the-bars mastermind of the kidnapping of the shipping tycoon Pericles Panagopoulos.
Panagopoulos was kidnapped in January 2009 and released after eight days, when a ransom of €30 million was paid.
While awaiting trial for the kidnapping, Vlastos tried to escape from Korydallos prison in December 2011 with three members of the armed anarchist group Conspiracy Nuclei of Fire.
The four used a pistol and knives to take hostage three prison guards and 25 visiting relatives of other prisoners. The four surrendered to authorities after a five-hour stand-off.
Vlastos had also tried to escape, unsuccessfully, in 1994 and 1998.