Fires occurred in the wider Browns Quay area.
A man has been arrested in connection with two suspected arson incidents in Limerick.
Gardai were alerted to a car on fire at Browns Quay at around 1:30 yesterday morning.
They received reports a number of hours later of a fire at a nearby business - with significant damage caused.
A man in his 40s was arrested in Limerick this morning and is being questioned at Mayorstone Park Garda station.
Investigators are still appealing for any witnesses to come forward.

Kildare Among Worst Affected Counties As 54,000 Lose Power Nationwide
Majority Of Councillors Vote To Suspend Pay Parking In Naas During Christmas Period
Children's Minister Announces Reforms Of Assessment Of Need Process, Admits System Is Broken
Ireland Secures Extension Of Nitrates Derogation To 2028, Minister Heydon Confirms
Watch: Backlash As Government Video Advises Young Adults How To Cope If They Move Back Home
Kildare Among Country’s Top Christmas Spenders As Average Outlay Tops €2,000
Kildare Under Orange Wind Alert From 11am Today
Gardaí Probe Whether Fatal Edenderry Firebombing Was Directed From Prison By Kildare-Offaly Gang