Pakistan says it has shot down two Indian military jets and captured a pilot in a major escalation between the nuclear powers over Kashmir.
India said it lost one MiG21 fighter and a pilot was missing in action.
Pakistani PM Imran Khan said the two sides could not afford a miscalculation with the weapons they had.
India and Pakistan – both nuclear-armed states – claim all of Kashmir, but control only parts of it.
They have fought three wars since independence from Britain and partition in 1947. All but one were over Kashmir.