Could be the 'Wizard' series by Grey Sapien (Combat Wizard, Wizard at Work, Talent), withdrawn from here and published under 'Jack L Knapp'. MC is in military initially, using his (initially weak) TK to help protect him and his troops, a failed result of a black govt program intended to develop telepathy as an unjammable comms, and which is shut down with extreme prejudice. He escapes with the aid of a nurse who has some TP, later recruiting an ex-sergeant who was searching for him, and finds they are able to pass on and develop their skills. They get involved in a turf war between drug dealers, use their talents to mine gold, retire to a small desert community, accidentally pass on some talents to the locals, and have to battle another esper with delusions of godhood.
Probably not, since I don't remember the poison gas, but they did get hit by an RPG which brought the building they were in down on them.