is this a good piece of flash fiction?

We haven’t slept in days, but then running for your life will do that to you. As I look around at the haggard group of survivors, all I can think about is the future of humanity. For all we know, we might be the only survivors on the planet. We settled down in the courtyard of a ruined shopping mall, sitting back to back to keep watch. When we left the compound one week ago, there were twelve of us. Now there are only five left. We try to sleep, but sleep doesn’t come easy. We pass the sleepless night on the nervous watch for them.
In the morning, we move silently through the ruins of what was once Houston headed west. Two days ago we returned to the compound that once offered safety. Everyone was dead, well almost dead. In this hell we find ourselves in, no one really dies. This disease, this mutation takes humans down to their barest instincts. All this time we never realized that violence was human nature. It is these things, these violent shells of the humans they once were; that we run from.
We walk past the remains of a large group of people that were trapped by a fence. The carnage is horrific, but we barely notice. We need to get to New Mexico, Terry would tell us. As if she knows what is waiting for us there. We hear the telltale grunts coming from down the street we were walking on. Our walking turns to a run as we try to make it to the large warehouse of the bus depot one mile away. The grunts become screams and incoherent yelling as they pick up our trail. From the sounds they are making, there must be several dozen of them. We have the firepower to take them, but we must make it to the depot.
By the time we get to the door to the depot, they are hot on our heels. Some are carrying weapons; clubs, bats sticks. Others intend to use their bare, blood soaked hands to dispatch us. The four of us with firearms set up a perimeter around Terry as she tries to open the door, which is locked. The blasts of the gunfire, the pinging of the brass as they fall onto the ground, the screams of the damned and the frustrated yelps from Terry all merge into one noise so loud you can’t even hear it. It took longer than is should have to get into the building, but we got in. All five of us pushed through the door, and Terry shoved it closed with just enough time to stop the rampaging beasts that were bent on avenging the deaths of those we killed. We sit in the silence of the hangar-like depot, panting. Around us were vehicles of all sorts, and even a gas pump! Fear and anguish mixed with cautious optimism with the new find. All that could make this discovery better would be a cache of ammunition, as all but one of us was out. We shook off this thought and ran through the vehicles, happiness and relief growing. Salvation!
From somewhere within the darkness of the building we had locked ourselves in, quiet grunting from a dozen beasts that were on the hunt……