* Witness says rail company added wagons before departure
* Wagons overturned, rescuers on the scene

At least three people were killed and many injured when a packed passenger train travelling between Cameroon's capital Yaounde and the port city of Douala derailed and overturned on Friday, witnesses said.

Camrail, which is operated by France's Bollore Railways , confirmed on its Facebook page that an accident had occurred near the train station in the town of Eseka, around 120 km (75 miles) west of Yaounde. Passengers put the time of the accident at around 11 a.m. (1000 GMT).
"There was a loud noise. I looked back and the wagons behind us left the rails and started rolling over and over. There was a lot of smoke," said a Reuters journalist travelling in a wagon near the front of the train.
He said that, before its departure from Yaounde, a railway employee said eight additional wagons had been added to the normally nine-wagon train to accommodate extra passengers, though it was unclear if that played a role in the accident.
The collapse of a bridge along the main highway between the capital and Douala had prompted increased numbers of passengers to undertake the journey by rail.
Joel Bineli, a passenger, told Reuters he saw the dismembered bodies of three fellow passengers on the tracks at the accident site. Social media users posted photos purported to have been taken at the scene of the accident which showed several wagons overturned on a slope beside the rail line.
"Rescue workers arrived and they are pulling bodies from the wagon. I've already counted around 40 bodies they've removed, but I cannot confirm if they are dead or wounded," said Rachelle Paden, another passenger.
Camrail said it had sent teams to the site but declined to give any further information on the incident. A Bollore spokesman would only confirm that an accident had occurred.
"There are many injured. We are still in the phase of evaluating the situation. We cannot give even a provisional toll," said a Camrail official, who asked not to be named.
Cameroon Transportation Minister Edgar Alain Mebe Ngo'o said a team of government officials from different ministries had been dispatched to Eseka. "What is certain is that there is a lot of damage, both human and material, due to the train derailment. But we cannot yet give a toll," he said.
Many rail lines in west and central Africa have a reputation for poor maintenance and failing to respect safety norms. Derailments are relatively common.
Though Bollore is generally viewed as a reliable operator, it experienced another major incident last month when part of a bridge along a line it controls in Ivory Coast collapsed under freight train.