Around 35 trains were stuck at various places in the region, Railway officials in Ambala said.
Trains bound for Delhi, Amritsar, Jammu, Ferozepur, Kalka and other places came to halt mid-way, they said adding Ambala-Kalka and Kalka-Ambala passenger trains were cancelled.
Delhi-bound Amrapali Express and the Paschim Express, heading towards Mumbai, were being operated by diesel engines, the officials said.
The signal system was also affected at a number of places due to the grid collapse.
