The BBC's Laura Bicker said US intelligence services would be monitoring IS chatter on the dark web to try to determine if he had been killed in the attack.
US forces have carried out an air strike targeting the Islamic State group militant "Jihadi John", the Pentagon has said.
There is a "high degree of certainty" that he was hit in the attack near Raqqa, in Syria, according to a senior military source.
Mohammed Emwazi, the Kuwaiti-born British militant, appeared in videos of the beheadings of Western hostages.
It is believed there was at least one other person in the vehicle targeted.
A US official told the BBC Emwazi had been "tracked carefully over a period of time".
'Jihadi John': US air strike targets Islamic State militant in Syria - BBC News