Video offers clues to missing girls
The potential witnesses are seen moments after two girls believed to be the missing 10-year-olds are seen in a sports centre car park in Soham, Cambridgeshire.
The police have also revealed more unconfirmed sightings of the girls, which suggest they were last seen walking southbound on a main road out of the village.
Officers are "very optimistic" the CCTV pictures can lead to a breakthrough if the four are able to provide important information about the girls' disappearance on Sunday.
The two men and two women get into a blue hatchback, believed to be a Renault Clio, and a red saloon car parked in the Ross Peers sports centre car park at 6.17pm.
The pictures were taken shortly before the last confirmed sighting of the two girls by four separate people at 6.30pm near the town centre.
They show the two girls walking across the car park, past the sports centre. Then about a minute later the group enters the picture, possibly having passed the girls seconds earlier.
Det Supt David Hankins, who is leading the investigation, said: "We believe they may hold vital information into the disappearance of Holly and Jessica.
"Perhaps they saw where they were heading and how they appeared."
Police also want to trace the owner of a white van and a motorcyclist seen in the car park.
DS Hankins said: "We're very positive and very optimistic about this piece of videotape that it may jog people's memories and encourage people who we think may be on this tape to come forward."
The pictures support the four sightings of the girls walking along Sand St, the lower end of the main street, towards the town centre at 6.30pm.
Staff at the sports centre told BBC News Online that Holly and Jessica had come in to buy sweets at a vending machine at about the same time.
Another four people claim to have seen the girls near the village war memorial about 15 minutes later.
The latest reported sighting is the pair walking down the A142 on the outskirts of Soham, towards Newmarket, at 7.00pm.
Meanwhile, Express Newspapers has offered a £1m reward, and two businessmen a total of £60,000, for information leading to the arrest and conviction of anyone responsible for the abduction of the best friends.
And The Sun and the News of the World newspapers have offered a £150,000 reward for anyone who provides information that leads to solving the mystery behind the pair's disappearance.
Det Supt Hankins broadly welcomed the rewards but warned they could lead to people giving false information.
"We really don't want the cranks coming forward with outrageous pieces of information which will distract our officers and waste time."
The parents have admitted it is likely the children have been abducted, because they would not have wandered off without permission.
The girls had been at the Ross Peers sports centre earlier on Sunday but had not asked permission to go back there in the evening.
Tests are being carried out on a white van seized from a caravan park in Wentworth, about ten miles away from Soham, after reports a vehicle was cruising the area on Sunday night.
More than 250 officers, including 60 specialist search experts, spent Wednesday checking waterways and river banks for clues.
Both girls are described as white, about 4ft 6in tall and slim. Jessica is tanned and has shoulder-length brown hair while Holly is fair and has blonde hair. They were both wearing Manchester United shirts at the time, and police have asked other youngsters in the area not to wear anything similar, to avoid confusion.




