Shoppers were evacuated from the Church Square Shopping Centre in St Helens this morning (Tuesday).
Bosses at the centre took the decision after a fault in the sprinkler system caused the fire alarm to activate.
The centre was shut for less than 30 minutes after its closure at around 10.20am.
Centre manager Steven Brogan said: "The centre was quickly and safely evacuated this morning, as a precaution, following a false fire alarm, believed to have been caused by water movement in the sprinkler system.
“The safety of customers and staff is our primary concern. I'd like to apologise for any inconvenience this may have caused."