LONDON, March 22 (Reuters) - Police are still searching for one of the two people believed to have launched Wednesday’s attack outside the British parliament building, assistant editor of the Daily Telegraph newspaper Christopher Hope tweeted, citing senior government sources.

A BBC journalist said two assailants were believed to have been in a vehicle involved in the attack.

“BBC understands from multiple sources two assailants in vehicle on Westminster Bridge,” BBC correspondent Dominic Casciani said on Twitter.