The head of Cyprus' navy, Andreas Ioannides, was among 12 people killed in blasts at a munitions dump which damaged the island's biggest power station, police has said.
The commander of the Evangelos Florakis base, Lambros Lambrou, and six firefighters also died in Monday's explosions.
Several huge explosions hit the Evangelos Florakis naval base early on Monday morning, when a brush fire approached dozens of storage containers holding gunpowder that had been confiscated in 2009 from a ship which had been heading from Iran to Syria.
"There were 98 containers of gunpowder. Two of them [caught] fire and huge explosions occurred," the Cyprus News Agency quoted a police spokesman as saying, referring to the explosions that struck shortly before 6am local time (03:00 GMT).
The base is located between the coastal cities of Limassol and Larnaca on the south side of Cyprus.
Costas Papacostas, the Cypriot defence minister, and Petros Tsaliklides, the commander of the Greek Cypriot National Guard, resigned from their posts hours after the incident.
A government spokesman ruled out sabotage. But the Greek defence ministry said it would be sending a team of explosives experts to aid investigations into the exact cause of the explosions.
"Following a request by the defence ministry of the Republic of Cyprus, Greece is sending expert personnel from the armed forces by C-27 military transport plane to assist the investigation," the ministry said.
Twisted road signs
State television broadcast images of damaged vehicles, twisted road signs and debris strewn across a wide area. Businesses located close to the site of the explosion reported that their windows had been blown out by the force of the blast.
Aliki Stylinaou, a defence ministry spokeswoman, said that the death toll could not immediately be confirmed, but local media reported at least 12 killed, with as many as 60 feared injured.
Speaking to Al Jazeera from the naval base, Alana Kakoyiannis, a witness, said: "There were 60 injured they were brought to the local hospital in Limassol. Most of them have been released, but there are still two in critical condition."
The dead included five firefighters, four National Guard members and two sailors.
"It looks like a bombed-out landscape," a witness told Sigma television.
Costas Gavrielides, a spokesman for the state-run electricity authority, said the blasts damaged the Vassilikos power station.
Yiannis Tsouloftas, an official with the utility, said the station had sustained extensive damage as a result of the concussion wave of the blast.
He said that it would remain offline till at least Monday, with the island's two smaller power stations attempting to cover electricity demand.
The Vassilikos power station is very close to the Evangelos Florakis navy base, where the explosions occurred.
"The power station failure here has had a rippling effect throughout the island. There have been brown-outs in nearby major city of Limassol and in the capital of Nicosia which is 85km away," Kakoyiannis said from the site of the blasts.
Petros Tsaliklides, the chief of the National Guard, told public radio that the containers that exploded had been seized from the M/V Monchegorsk, a Cypriot-flagged vessel, in 2009.
Visiting the site of the blast later on Monday, Dimitris Christofias, the president of Cyprus, said: "Today we mark a dark day in July for the Cypriot nation and its people. We are shocked by this event, not just from the damage but from the loss of human life and the injury to many of our people.
"I want to express my condolences and support to the families of the victims who lost their lives carrying out their duties dutifully. Damage can be repaired, but lives cannot return."