Russian investigators say they have detained two employees of the Moscow subway where 22 people died and more than a hundred were injured in a train derailment.

The Investigative Committee said in a statement Wednesday that they have detained the head of the track department and his deputy. Investigators said a new rail switch at the point where the train left the tracks was not properly installed during repair works in May and was in fact attached to the rail by a single wire.

The rush-hour accident on Tuesday killed 22 people and hurt 136. More than 1,100 people were evacuated from the train, which was stuck between two stations in Moscow's west, in a rescue operation that lasted more than 12 hours.