Thousands of people spent the night outdoors in the Spanish city of Lorca in fear of further tremors after Spain's worst earthquakes in 50 years killed eight people and injured dozens.

Francisco Jodar, the mayor of the town, told reporters as many as a third of Lorca's 90,000 residents spent
the night outdoors after Wednesday's earthquake.

A Murcia regional government statement said eight people, including one child, had died. A total of 167 people were treated in hospitals in the city.

Two rare earthquakes struck the region in quick succession on Wednesday, also causing major damage to historic churches and public buildings, officials said.

The first quake measured 4.4 while the second was of 5.2 magnitude.

Masonry and rubble filled some streets in Lorca, which dates back to Roman times and also has some medieval structures. Many cars were crushed by the quake that struck at 6:46pm local time.

On Thursday, people prevented from returning to their homes damaged by the quake, queued for food from emergency workers. Makeshift camps had been set up in parks and a trade show centre in the city.

"We spent the night outside here in the square. The emergency workers are giving us food and blankets," Edgar Rosales, an Ecuadorian immigrant, said.

"We're not allowed to go into our apartment until an engineer comes and looks at our building."

Troops sent to help

A military task force of 200 troops was sent to the affected area to provide aid and cordon off dangerous buildings.

Part of the front of a badly damaged church collapsed hours after the quake and other buildings were considered unstable.

Spanish TV showed images of cars that were partially crushed by falling rubble, and large cracks in buildings.

This was the deadliest quake in Spain since 1956, when 12 people died and some 70 were injured in a quake in the southern Granada region, according to the National Geographic Institute.

It says Spain has about 2,500 quakes a year, but only a handful are actually noticed by people. Spain's south and southeast are the most earthquake-prone regions.

The quakes in Spain come amid rumours in Italy of devastating shakes striking the capital Rome, causing residents to flee in panic.