1999 Dodge Stratus engine wont fire

Hi. My wife was driving home the other day on the freeway and she said she car just stopped running. She gave me a description of saying she was doing about 65 mph and her rpm's were about 1500 or so as she says. And then she said her rpm's went up to like 3000 or 4000 then a loud noise popped under the hood and the rpm's just died and now the engine wont fire over. Ive checked the spark plugs and there fine. And I pushed on the gas valve to see if its getting gas and it is. You have any suggestions why it would make a loud pop noise and then suddenly die and not turn over. And when you try to turn it over it just looks like the battery is dead and wont fire but it turns on just wont start. Thank you. Hoping for some good advise