NAIROBI, Kenya (CNN) -- More than 100 people were killed and several dozen wounded when an overturned petrol tanker exploded in Kenya early Sunday, authorities said.

The blast is the second multi-fatality incident in the east African country in four days. A supermarket fire in Nairobi on Wednesday killed at least 27 people, with another 57 still missing.

The tanker explosion occurred near Molo, a small town in the Rift Valley Province -- about 130 kilometers (80 miles) from the capital, a spokesman for the Kenyan police said.

The tanker overturned along a highway spilling gallons of gas which hundreds of residents rushed to scoop up, said Titus Mung'ou of the Kenyan Red Cross.

"People were lining up trying to get the fuel," he said. "They were siphoning off petrol for over an hour. Some people had drilled holes in the tanker and were charging a fee for the assembled crowd."

The vehicle exploded about an hour later, apparently after one of the residents lit a cigarette or started a fire at the crash site, Mung'ou said.

Four policemen, who were trying to control the crowd, were believed to be among the victims, Mung'ou said.

Another 117 people were wounded in the blast, police said. The figures are expected to rise, officials said.

The Red Cross sent more than 80 people to help with rescue efforts. Those who were seriously wounded were flown to a hospital in Nairobi.

Meanwhile, the death toll from last week's Nairobi supermarket fire rose to 27 on Sunday, the Red Cross said.

Rescue workers found the latest victims as they searched through the rubble of the scorched structure in downtown Nairobi.

The fire ignited Wednesday afternoon during a somewhat busy hour in the 24-hour Nakumatt supermarket.

Police launched a criminal investigation to look into allegations that security guards locked people into the burning building. Employees of the supermarket refused to comment on the allegations.

The fire angered Kenyans for what they perceived as a lack of disaster preparedness.

Emergency numbers failed to work and water ran out during attempts to put out the fire, said Mung'ou of the Kenyan Red Cross.

"There is the need to strengthen the capacity in handling fires," Mung'ou said.

All About Kenya • Nairobi