April was last seen by another child getting into a grey or light-coloured van wearing a purple knee-length coat with grey fur around the hood, a white polo top and black trousers.
She is thought to have been abducted.
Police are currently viewing CCTV, for clues about the abduction. Two helicopters were deployed to scour the area along with dogs as part of police operations.
Detective Superintendent Reg Bevan said:
“It is still early days in the investigation and we are still speaking to witnesses to gather as much info as possible. These witnesses are children and speaking with them is a delicate and time consuming process.
“I would like to return to the description of the vehicle, and I am mindful that we are still in the process of speaking to these children, so I am anxious that we only provided as accurate information as possible.
“What the witnesses have told is that the vehicle looks like a van, they describe it as small at the front and large at the back, so it could be interrupted that this could be something similar to a Ford Connect type van or a Landrover.
“Furthermore April has been described as getting into the driver’s side of the vehicle. This may be because she got in with the driver or that it is left hand drive vehicle.
“We still believe that the van is grey or light coloured, but again these things can be affected by failing light and street lamps.
“We are following expert advice and research which says that in situations like this you concentrate your searches in the immediate area and then widen it out. This is what we are doing.
“If you were in the area of Bryn y Gôg yesterday evening at around 7pm or you recognise the additional information about the van we have provided please call the incident room on 0300 2000 333. And please get in touch if you have any footage which may assist in our inquiries. If any pieces of information trigger something please get in touch.”
Hundreds join search
Hundreds of residents from the market town have also joined in the search and are co-ordinating their efforts at the Machynlleth Leisure Centre.
They were divided into groups of 20 by the police and sent out into the area, including the mountains with the help of local moutaineering experts. The town, which only has a population of 2,000, sits on the southern outskirts of Snowdonia National Park.
Meanwhile volunteer Anwen Morris appealed for more people to come forward and help. Many have already taken time off work to look for April and have been out through the night on quad bikes and off-road vehicles.
Ms Morris told Sky News: “We need bodies down here. We need people in cars, we need people on foot to search the town. We need people up on the mountain. We need anybody that is in the area that can help.”
Powys County Councils said refuse and recycling collections had been suspended in the town on Tuesday so council staff could help with the search.