The script identifies the objects they shoot thusly;
The startled guards are momentarily dumbfounded. Luke and Han have
already pulled out their laser pistols and are blasting away at the
terrifying Wookiee. Their barrage of laserfire misses Chewbacca, but
hits the camera eyes, laser gate controls, and the Imperial guards.
The officer is the last of the guards to fall under the laserfire just
as he is about to push the alarm system. Han rushes to the comlink
system, which is screeching questions about what is going on. He
quickly checks the computer readout.
Star Wars: A New Hope - Final Draft Screenplay
They continued to shoot security sensors
Han shouted, “Go get him!” and grabbed a blaster from a fallen guard.
The lieutenant finally realized that Han and Luke weren’t real
stormtroopers and reached for his own blaster. Han disabled him. Then
he, Luke, and Chewbacca kept blasting until every security sensor was
a shattered mess.
Star Wars: A New Hope - Jnnior Novelisation
and energy-rate controls
Both he and Luke had darted clear of the rampaging Wookiee, pulled out
their pistols, and were blasting away at him. Their reaction was
excellent, their enthusiasm undeniable, and their aim execrable. Not a
single shot came close to the dodging Wookiee. Instead, they blasted
automatic cameras, energy-rate controls, and the three dumbfounded
guards.
...
Pointing his pistol at the [Comlink] panels, Solo blew the instrumentation to silent scraps.
Star Wars: A New Hope - Official Novelisation