Firefighters in Alameda work a 48 consecutive hour shift. They work together as a three person crew on a fire engine or truck or as a two person crew on a fire ambulance. Keeping the crew together at all times is critical to facilitate responses to emergencies. Breaking up a crew to send one person shopping or on other details would delay these responses.
While they are on duty they eat their meals at the firehouse. In order to purchase the food they need they shop at local establishments. When you see a fire engine or fire truck at a grocery store it is because the firefighters assigned to that engine or truck are still able to respond to an emergency from that location. They often leave their groceries behind to respond and then come back afterwards to finish their shopping.
One last fact, firefighters pay for all their own meals while they are at work.
