Well, looking at what I thought I had written vs. what really is, the context is a lacking.
The shopkeeper is the screamer. Have one of the people outside be his wife. Since your heroes are wearing uniforms, she'll go to them first and beg for help. That will drive them inside a lot easier. They can't go around to the back quickly, so enter in through the front door (lower one in the picture). I would also put a wide window just to the right of the door, over the book cases, with the window already smashed so a hero can choose to enter that way.
Extra Read-Aloud - right after the first one.
Next to you, amidst the recovering townspeople, another wail is heard and a woman wearing a fine but muddied red cloak pushes her way towards you. "Please officers, my husband! He's in there with... with... those ruffians. He's hurt, please help me!" As if to underscore her plea, another flash erupts, and the front window shatters as a bolt of lightning dances through and strikes one of the previously injured onlookers. He falls to the ground without a sound.
Now the issue is one of how to get in when there is an obvious gauntlet. One of the Storm Mages should be looking out the window, so a bit of stealth and a distraction at the door could provide the opportunity to get in and slip between the bookcases. It's a small space, but there is a lot of cover so sneaky things can happen on both sides...
