Celebrations of the Dutch national holiday Koninginnedag have been cancelled, both in The Netherlands and abroad.

The embassy of The Netherlands to Bulgaria cancelled the celebrations planned for the evening of April 30 in Sofia.

Earlier during the day, at the celebrations in Apeldoorn, a driver in a black Suzuki Swift ploughed into a parade that included the bus with the Dutch royal family.

Four people were killed and at least a dozen were wounded.

Eight people had been taken to hospital, Dutch media reported.

The driver has been taken to hospital to be operated and has been arrested. His home was being searched by Dutch police.

The man was not known to the police and nothing was known about his mental health, a police spokesperson said at a media conference.

Police suspected it was an attempted attack on the royal family.

The drama happened as the bus with the royal family was about to enter palace Het Loo in Apeldoorn and within sight of the royal family.
The car broke through police blockades at high speed, hitting audience members in its path and ended its ride against a monument next to the entrance of the palace.
Some witness reports say the car had been sent away at police blockades earlier.
Crown-prince Willem-Alexander and his wife Maxima where seen watching the events unfold in horror.

Dutch queen Beatrix said in a televised speech "what started as a beautiful day, has ended as a horrifying drama that deeply shocked us all."

The family was speechless, the queen said.

Almost all festivities in the country have been cancelled following the events in Apeldoorn.