A light aircraft has crashed on to a main road but managed to avoid hitting any cars.
South Wales Fire and Rescue Service said the three people on board survived the incident on the A40 near Abergavenny, Monmouthshire.
It said they were treated at the scene for minor injuries and taken to hospital as a precaution.
A train had to make an emergency stop because of falling power cables as a result of the plane coming down.
Martin Barnfield, who was driving on the road at about 11:00 BST, said: “We saw a big plume of smoke. A few hundred yards on we saw the crash.
“It looked like it was taking off but wasn’t able to. It flipped over onto the westbound carriageway. The heat and explosion was immense.”
Eyewitnesses on social media suggested those on board were pulled from the aircraft before it burst into flames.
The road is currently closed between Raglan and Abergavenny and Transport for Wales said rail services in the area were severely affected.
Rhodri Jones, who lives about two miles from the scene at Llanover said: “I was in the house and heard a loud explosion.
“Initially we thought it was rail crash because the line is nearby. There was thick smoke.”
BBC reporter Rhodri Tomos, who was on the train said: “The guard said that a light aircraft has crashed into some power cables and the cables have hit the train.
“We could smell some burning and we were at a stop for about 15 minutes, but we’re moving again now.”
Gwent Police said in a statement: “The aircraft was reported to have made an unscheduled landing in the area, colliding with overhead wiring.
“Three occupants of the light aircraft were treated by paramedics at the scene. Their injuries are not life-threatening.”
Motorists have been asked to avoid the area and use alternative routes.
It is the second time in three years in which a light aircraft crashed on the same stretch of road, There is a private landing strip nearby.