Two Islamic extremists are said to be the focus of the Dortmund attack probe, and one has been detained.

Three explosions occurred as a bus carrying the Dortmund football squad travelled to the Signal Iduna Park stadium for Tuesday evening’s Champions League quarter-final first-leg tie with Monaco.

Defender Marc Bartra was injured in the attack, which left him requiring surgery on a broken bone in his wrist.

The tie was subsequently postponed for 24 hours.