The Greek island of Crete has been hit by an earthquake, killing one man and injuring 20, while damaging homes and churches and causing rock slides near the country’s fourth-largest city.

The quake, which had a preliminary magnitude of at least 5.8, sent people fleeing into the streets in the city of Heraklion, and schools were evacuated. Repeated aftershocks described by witnesses as feeling like small explosions rattled the area, adding to damage in villages near the centre of the quake.

“The earthquake was strong and was long in duration,” Vassilis Lambrinos, the mayor of Heraklion, told Antenna television.

The Athens Geodynamic Institute said the quake struck at 9.17am (6.17am GMT), with an epicentre 246km (153 miles) south/south-east of the Greek capital, Athens.

Hospital officials said 20 people had been treated for injuries.

International and domestic flights to Heraklion airport were unaffected by the quake, while the region’s hoteliers’ association said there was no serious damage to any hotels in the area, which includes many popular holiday resorts.

Municipal construction vehicles helped clear a path for the emergency services, scooping up rubble and knocking down a badly damaged apartment block balcony.

“This is not an event that occurred without warning. We have seen activity in this region for several months. This was a strong earthquake, it was not under sea but under land and affecting populated areas,” Gerasimos Papadopoulos, a seismologist, said on Greece’s state broadcaster, ERT.

The European-Mediterranean Seismological Center and the US Geological Survey gave the quake a preliminary magnitude of 6.0, with an epicentre 7km (four miles) north of the village of Thrapsano. It is common for different seismological institutes to give varying magnitudes for an earthquake.

Greece’s climate crisis and civil protection ministry said one man had been killed. He was pulled from the rubble of a partially collapsed church in the village of Arkalochori, close to the epicentre, authorities said. Local media said the victim was a 65-year-old builder who had been working inside the church when the roof collapsed on him.

Giannis Oikonomou, a government spokesman, said there were no reports of people missing or trapped under rubble.

Efthimios Lekkas, a seismologist, who heads Greece’s Earthquake Planning and Protection Organization, said inspections of critical buildings such as schools and hospitals had already begun.

“We are urging people who live in damaged older buildings to remain outdoors. One aftershock can cause a collapse,” Lekkas said from Crete. “We are talking about structures built before 1970. Structures built after 1985 are built to a higher standard that can withstand the effect of an earthquake.”

Christos Stylianides, the climate crisis and civil protection minister, who traveled to Crete, said a state of emergency was being declared in the area. Local media said hundreds of homes had been damaged, including more than half the houses in Arkalochori.

Civil protection officials said tents were being set up for residents whose homes had been damaged, with capacity for up to 2,500 people.

The fire department said it was flying 30 members of its disaster response units with sniffer dogs and specialised rescue equipment to Crete, while all of its disaster response units and fire department services on Crete were placed on general alert.

Numerous aftershocks have been reported in the area, with the EMSC giving a preliminary magnitude of 4.6 for the two strongest.

Greece lies in one of the most seismically active parts of the world, but strong quakes that cause extensive loss of life or widespread damage are rare. In 1999, an earthquake near Athens killed 143 people.