A lot of things happen all at once.
From the perspective of the pirates, one group moves to flank, one group stays in the middle to provide covering fire, and one group moves forward to engage in melee.
From the perspective of the ... 'heroes', let's go with that ... Commagene rigges the rear entrance with two grenades, then moved out of the building to the opposite side. Maeve was in cover in the burnt-out hulk of a riot control vehicle, shooting at the pirates as they emerged to engage in melee, and Zeke was on the left flank, doing the same.
On the right flank, the grenades go off just as the pirates enter the building. In the center, the melee group are caught in crossfire - and to everyone's complete surprise, on the left flank a tech priest walks around a corner and right into the battle. Seeing this, Zeke is quick to send a burst of machine chatter to the newcomer, asking for aid, or at least making sure he doesn't help the wrong side.
++ BY THE OMNISSIAH, GREETINGS COG-BROTHER - TAKE COVER, QUICKLY, AND AID US IF THE MACHINE SPIRITS WILL IT SO ++
That done, Zeke opens up with his las rifle, showering the pirates in hot laser fire.
Lexent, please roll initiative - and any attacks and damage rolls you deem reasonable =)
-------------------------- Results --------------------------
Commagene's grenades go off, right at the most opportune moment. She doesn't stick around to see the results, but just as the rear entrance opens and the pirates charge in, the grenades go off right beside them. She tosses another one into the warehouse as a parting gift. It seems unlikely anyone remains alive in there.
Between them, Maeve and Zeke open up a crossfire of las bursts, making short work of the lead ganger and severely wounding another.
The final group of gangers open fire on Maeve, but only one of them has any appreciable succes, doing cosmetic damage to her cover. One of the others mutters in frustration as his gun jams, and he fiddles with it to make it fire once more.