An automated storage and retrieval system comprising a fire extinguisher assembly for extinguishing fire on and within the automated storage and retrieval system , wherein the automated storage and retrieval system further comprises - a rail system comprising - a first set of parallel rails arranged in a horizontal plane (P) and extending in a first direction ( X ), and - a second set of parallel rails arranged in the horizontal plane ( P ) and extending in a second direction ( Y ) which is orthogonal to the first direction ( X ); which first and second sets of rails form a grid pattern in the horizontal plane ( P ) comprising a plurality of adjacent grid cells of length L gc and width W gc , each comprising a grid opening defined by a pair of adjacent rails of the first set of rails and a pair of adjacent rails of the second set of rails ; - a plurality of stacks of storage containers arranged in storage columns located beneath the rail system ; and - a plurality of container handling vehicles for lifting and moving storage containers stacked in the stacks , the container handling vehicles being configured to move laterally on the rail system above the storage columns to access the storage containers via the grid openings , wherein the fire extinguisher assembly comprises - a service vehicle comprising propulsionmeans allowing movement of the service vehicle and a fire extinguisher compartment for containing firefighting equipment ; and - the firefighting equipment contained in the fire extinguisher compartment , for extinguishing fire on and beneath the rail system using fire extinguishant, characterized in that the propulsion means allows movement of the service vehicle across the rail system and comprises a caterpillar track configured to drive on top of the rail system , wherein the caterpillar track has a length L pm at the level of the horizontal plane (P) exceeding a length corresponding to a diagonal length across a maximum grid opening of the rail system when the service vehicle is moving across the rail system . - a rail system comprising - a first set of parallel rails arranged in a horizontal plane (P) and extending in a first direction ( X ), and - a second set of parallel rails arranged in the horizontal plane ( P ) and extending in a second direction ( Y ) which is orthogonal to the first direction ( X ); which first and second sets of rails form a grid pattern in the horizontal plane ( P ) comprising a plurality of adjacent grid cells of length L gc and width W gc , each comprising a grid opening defined by a pair of adjacent rails of the first set of rails and a pair of adjacent rails of the second set of rails ; - a first set of parallel rails arranged in a horizontal plane (P) and extending in a first direction ( X ), and - a second set of parallel rails arranged in the horizontal plane ( P ) and extending in a second direction ( Y ) which is orthogonal to the first direction ( X ); which first and second sets of rails form a grid pattern in the horizontal plane ( P ) comprising a plurality of adjacent grid cells of length L gc and width W gc , each comprising a grid opening defined by a pair of adjacent rails of the first set of rails and a pair of adjacent rails of the second set of rails ; - a plurality of stacks of storage containers arranged in storage columns located beneath the rail system ; and - a plurality of container handling vehicles for lifting and moving storage containers stacked in the stacks , the container handling vehicles being configured to move laterally on the rail system above the storage columns to access the storage containers via the grid openings , - a service vehicle comprising propulsionmeans allowing movement of the service vehicle and a fire extinguisher compartment for containing firefighting equipment ; and - the firefighting equipment contained in the fire extinguisher compartment , for extinguishing fire on and beneath the rail system using fire extinguishant, <EOS>