A broken track has disrupted train services between Perth and Inverness.
Engineers are at the site of the damaged rail at Dunkeld and Birnam. Network Rail said services would be restored "as quickly as possible".
ScotRail said it was running a shuttle bus service between Perth and Pitlochry.
Additional buses have also been operating between Perth and Inverness to supplement the train service, it added.
Network Rail Scotland said: "Our engineers are on-site working to inspect the damaged track and put plans in place to repair and reopen the railway for customers.
"We understand the inconvenience this incident has caused passengers and are working as quickly as possible to restore services."