Eastern Province Commissioner of Police Grace Chipalila said the incident happened when the parents left the children alone in the vehicle.
Ms Chipalila told journalists in Chipata yesterday,May 12th that the tragedy happened on Saturday between 09:00 hours and 11:00 hours.
“We had a sad accident on Saturday. Five adults took five children aged between one and eight years on a maize field visit but the children were left alone to play in the vehicle whose doors were open,” she said.
Ms Chipalila said while the children were playing, they locked themselves in the vehicle and failed to open the doors.
Three of them died on the spot and one was admitted in the intensive care unit (ICU) at Nyimba Hospital but died later.
Ms Chipalila said an 8-year-old child survived.
Police are investigating the matter to find out exactly what happened.
One of the adults, Memory Ngulube, 24, reported the matter to police.
Nyimba District Commissioner George Phiri said in a separate interview that three of the children are of the same family.
Mr Phiri said the mother of the children entrusted an older boy to look after his siblings while they were harvesting maize.
He said the children locked themselves in the vehicle and after almost two hours, the parents returned only to find three of the children unconscious and one of them gasping for air.
He said by the time the children were rushed to hospital, three had already died and the doctor declared them as brought in dead (BID).
The fourth died in hospital the following day.
The vehicle had been left in police custody in Nyimba.
Meanwhile, two people died in separate incidents in Sinda and on the Chipata-Lundazi road between Friday and Saturday.
Ms Chipalila said a 47- year-old woman, Alice Ngoma, died at Katete’s St Francis Mission Hospital after the vehicle they were travelling in from a wedding in Sinda slammed into a tree.
She said the accident happened on Friday when a Mazda vehicle being driven by Loveness Kuwa and with 13 passengers hit into a tree.
Ms Chipalila said the driver lost control of the vehicle when the bonnet flew open.
In another incident, a cyclist died after being hit by a bus as he tried to switch lanes on the Chipata-Lundazi road on Sunday.
Kada Mwale died at Chipata General Hospital from head injuries and the driver of the bus, Lewis Mwaba of Lusaka’s Makeni area, has been detained to help with investigations.
And Ms Chipalila has warned police officers against a tendency of asking for fuel each time members of the public report a crime.
She said the police have a mandate to protect the citizens at no fee.