Ghana's president, John Mahama, has called for three days of mourning to begin on Monday after scores of people were killed in an explosion at a petrol station in the capital, Accra.

Around 90 people who sought shelter from flooding overnight at the state-owned GOIL petrol station near a busy downtown intersection were killed, authorities said on Thursday.

In addition to the dead at the petrol station, local media reported that dozens of people drowned in various parts of the city following two days of torrential rains.

The combined death toll from the explosion and flooding has crossed 150 and again raised concerns over the city's inadequate infrastructure.

Al Jazeera's Ama Boateng, reporting from Accra, said: "This is a very busy area of Accra. Lots of people. Lots of car traffic.

"And because of the heavy rains people gathered at this gas station to seek shelter and this explosion happened."

TV footage showed corpses being piled into the back of a pickup vehicle and other charred bodies trapped amid the debris.

Floodwaters around the site hampered rescue and recovery efforts.

Officials at the nearby 37 Military Hospital said its morgue had reached capacity.

Death toll 'catastrophic'

President Mahama visited the scene, calling the death toll "catastrophic" and offering condolences to families of the victims.

"Steps will be taken to ensure that disastrous floods and their attendant deaths do not occur again," he said.

He also announced the creation of a 50 million cedis ($12m) recovery fund as flooding killed dozens.

It was Ghana's single worst disaster since more than 120 people died in May 2001 in a stampede at the national stadium during a football match, a police spokesman said.

Michael Plange, who lives a few blocks away, said many people had taken shelter under a shed at the station from the rain and were hit by the explosion.

The flooding "caused the diesel and petrol to flow away from the gas station and a fire from a nearby house led to the explosion", said Billy Anaglate, spokesperson for Ghana's national fire service.

Infrastructure deficit

The explosion is likely to intensify criticism of the government's failure to improve the infrastructure.

Though the downpours this week have been especially bad, heavy rains in June are not unusual yet drainage systems in Accra remain inadequate.

The area where the blast occurred is a heavily trafficked section of central Accra with several banks and other offices in addition to residences. Multiple bus terminals connect the area to the rest of the city.

Throughout Accra, drivers caught in the flooding abandoned their cars on the road.

The education ministry instructed all children who were not already at school on Thursday morning to stay home.

The city is also grappling with an energy crisis resulting in blackouts lasting for as long as 48 hours in recent years, causing large-scale demonstrations drawing everyone from blue-collar workers to local film stars.

About a dozen people were taken to hospital after Thursday's blast in the petrol station in Accra [Reuters]

Source: Al Jazeera and agencies