Ghanaians are being questioned about the cause of a petrol station fire in the capital, Accra, in which some 150 people died on Wednesday night.
It is believed flood waters carried fuel from a garage storage tank towards a nearby fire, causing the explosion.
But the fire service is trying to establish where exactly it started.
The salvage operation is continuing as residents say they are finding more bodies of victims killed in the fire and the flooding that has hit the city.
Three days of national mourning will start for those all those who died on Monday, once the official death toll is known, the government says.
President John Dramani Mahama has described the incident as "catastrophic" and "unprecedented".
People had sought shelter at the petrol station after being stranded by flooding and rain; buildings adjoining the garage were also burnt.
The president has vowed to take tough measures to stop people building illegally on stream beds during the dry months.
They pour rocks and sand onto the beds before constructing buildings, so when the rains come the water rises and is diverted into nearby communities causing flooding.
"I think that the time has come for us to remove houses out of water and the public should understand that it is necessary to save everybody else," President Mahama said.
One of the investigators, Harriet Nunoo, told our reporter that it had been established that fuel had spilled from the petrol station and mixed with flood waters sweeping into nearby homes, where it had come into contact with naked fire.
The BBC's Sammy Darko in Accra says tensions have been running high as fire investigators question witnesses.
Some young men became angry, denying they caused the fire.
One witness suggested that the fire started when a cigarette was dropped, our reporter says.
Ghanaians are using the hashtag #ThisMustStop to vent their feelings, accusing those in power of not doing enough to ensure flooding does not happen.
"It's amazing how Gov't thinks we are all idiots! We repeat the floodtalk every year and do NOTHING about it," said George Kojo Anti.
Other tweeters called on residents of the capital to take some responsibility and pick up litter that ends up clogging up the drains. "We litter our surroundings without thinking and tend to put the blame on the government when something goes wrong with sanity," abdulbassit tweeted.
Following an emergency meeting of cabinet and security chiefs on how to tackle flooding, the government said it would release £9m ($14m) to help flood victims.
In total, an estimated 200 people have died in the petrol station fire and flooding across the country, the interior ministry has said.
Throughout Thursday night and into Friday morning the emergency services in Accra have been removing cars and other rubbish that have been washed into storm drains, our correspondent says.
All over the city, people are trying to salvage their belongings from homes and businesses affected by the flooding, he says.
Electricity has been restored to some areas after electricity sub-stations were damaged in the flooding but some internet services are still down, he says.
It has been raining again and more downpours are expected over the weekend, bringing fears of further flooding, our correspondent says.