In general a report of "victims trapped" should not cause any major changes in your initial operations. They may cause slight alterations such as where you take your line, which window you VES, etc. However your plans/SOGs should already be setup assuming there are persons trapped. When added information increases the likelihood of entrapment we should be doing what we always do, just harder and faster!
Remember all tasks work in support of each other on a fire. Abandoning one will wreak havoc on the others. The results do not improve the victims’ chances and put us at greater risk. I have seen many incidents quickly go south when everyone "loses their cool" after a report of entrapment. Important tasks such as water supply, ventilation, and fire attack are abandoned because we all think we're just going to dash in and "save the baby". When this happens we are often unsuccessful in our firefighting efforts, the victim usually perishes, and we frequently hurt firefighters due to our scatter-brained actions. By cutting corners we lose, and often then find out there wasn't anyone trapped!
As was the case last night, reports of a victim do not mean there IS one. And reports of no victims (or reports of "everyone's out") do not mean there isn’t one. Deploy in response to conditions and always give any known OR unknown victim their best chance. Don't guess on "survivability" from the front yard - you don't know what you don't know. Our job is to react to conditions, not guesses, and give them a chance. As I was once taught by a veteran truck officer, they are not out until our searches SAY they are out.