The abduction of a five-year-old girl on Monday night is "every family's worst nightmare", police have said.
Detective Superintendent Reg Bevan, from Dyfed Powys Police, told a press conference that getting "vital" information from the children who witnessed April Jones getting into a van is a "delicate and time-consuming" task.
April was last seen by another child getting into the driver's side of a grey van which drove off in the Mid Wales town of Machynlleth at about 7pm on Monday.
Mr Bevan said: "Clearly, it would be every family's worst nightmare to suffer a child going missing in these circumstances."
He emphasised the difficulties of getting accurate information from the young children who were playing with April when she disappeared.
"I am mindful that we are still in the process of speaking to these children," he said. "That is delicate and time-consuming. We are trying to extract exactly what they have seen and we are very anxious to provide the most accurate information we can without misleading anyone in any way."
The description so far of the van the youngster was seen getting into is a grey vehicle, small at the front and large at the back, Mr Bevan said.
He added: "That could be interpreted as something small to a Ford Connect van, something like a Land Rover, and also that April got into the driver's side. "That may well be that she got in with the driver, but of course that could mean that it's a left-hand drive vehicle. The colour has not changed, that's as we initially gave it - grey."
Mr Bevan repeated earlier pleas for any information, no matter how small. He said the force would be combing through CCTV, both municipal and private, to find clues about the abduction of the five-year-old.