Getting Sued For A House Fire

Hello, in August of 2022 my girlfriend and I and our roommates had a fire break out in our apartment complex, no one was injured but the place has since been condemned. At the time of the fire my girlfriend and I were both still at work and had been for 6+ hours at this point only getting there after firefighters had arrived. For the first couple days and afterwards we were told the cause was determined unknown and we had gotten our security deposits back.

This brings us to today, a sheriff came to our door and served us with a writ of summons, it is from the insurance company which our landlord used I’m guessing. They are suing us for negligence, essentially they said we were cigarette smokers ( we are not but we do partake in the greenery but we only use a bowl which was mainly used in the kitchen) and didn’t properly dispose of a cigarette. I should note that the fire started on our balcony on the 2nd floor, we do have a upstairs neighbor whose balcony is right above ours. ( who I’ll get to in a second) after receiving this summons we contacted our old roommates to see if they had gotten theirs yet, they hadn’t but while talking with them they had brought up a couple good points we were not aware of fully. 1) according to them they had checked the Fire Marshall’s report recently and it’s still cause unknown ( we are still waiting to hear from the Fire Marshall to confirm or deny this) 2) the day of the fire our upstairs neighbor had said she was smoking a cigarette on her balcony no more than 10 minutes before the fire happened

As it stands right now it is still early on in everything as we’ve only just gotten the summons, with the summary out the way I can now get to my questions

How do we respond to this summons? It says we have 30 days to submit a response and am unsure if we need to get a lawyer or if this is an us responding moment. As we weren’t there and aren’t cigarette smokers I’d like to innocently respond With us not being home with documentation of time ins and outs what’s the likelihood of their charge sticking? Also with the now inclusion of our upstairs neighbor being a cigarette smoker with multiple witnesses hearing her state she had a cigarette right before the fire is it possible it’d be turned over to them? If we do need a lawyer what area of law should we be looking for help wise? If there r are any programs or services available that’d help us out that I’m unaware of that’d be lovely as well Any help/advice is appreciated beforehand, thanks and have a good day