FOUR people were killed and three were critically injured yesterday morning in separate road accidents involving concrete mixers.

Police said one of the trucks lost control and crashed into a row of houses in Liuzao Town, killing two people.

Witnesses said the accident happened about 3:30am at Liuzao Town in Nanhui District when a concrete mixer crashed into the roadside of Zhouzhu Highway, knocking down three village houses.

A couple, about 40 years old, and a senior were buried under the rubble. Paramedics pronounced the couple dead after rescuers pulled them out of the wreckage. The elderly woman suffered serious injuries to her head, chest and stomach and was still in critical condition in hospital late yesterday.

The couple's two sons, aged 14 and 12 years, escaped the accident as they happened to be sleeping at their uncle's place, neighbors said.

Police suspected the concrete mixer ran out of control after the driver fell asleep.

The driver has been detained by police along with the driver in a second accident yesterday.

In a separate case, a truck hit and killed a pedestrian and a moped rider about 8:20am at the crossing of Longwu Road and Shilong Road.

Witnesses said the truck was trying to get through the crossing ahead of a red light.

Police said the pedestrian was killed instantly when he was thrown about 10 meters from the impact of the truck.

Police said the truck lost control after hitting the pedestrian and crashed into a bicycle lane, knocking down a dozen mopeds.

A 59-year-old Shanghai man, one of the moped riders, was pronounced dead at hospital.

Chen Xinmiao, a 19-year-old student at a local university, received serious head injuries. The other critically injured victim was a 34-year-old man from Henan Province. They were both being treated at hospital yesterday afternoon.