The issue is whether the landlord is at fault. Without in any way diminishing the threat, the trauma, or the need to do what is right to protect your children, if the landlord has done nothing wrong, the law does not punish the landlord by allowing you to terminate your lease without paying the appropriate amounts, fees, etc. So if this was an employee of the landlord, or if it was a tenant about whom there had been warnings, complaints, or who had engaged in prior acts like this, you would have a good case to terminate the lease without penalty, on the grounds that the landlord was at fault by not taking steps to protect tenants and their children from a known threat or a threat under its control. If however there was no prior warning of this, then the landlord did nothing wrong, and you probably cannot terminate without paying the appropriate amounts.