Federal Magistrate John Coker says he "went cold" when his son David called him to say he and his girlfriend had been shot during a series of co-ordinated terrorist strikes in India's financial capital.
Foreign Minister Stephen Smith said up to 26 Australians were believed to have been in the Taj Mahal and Oberoi/Trident hotels that were attacked by armed Islamic militants.
One Australian man has been confirmed dead and there are grave fears that another Australian could be among the estimated 125 people killed during the attacks.
Townsville law graduate David Coker (23) and his Sydney partner Katie Anstee (24) were eating at Mumbai's Cafe Leopold when the gunmen opened fire, shooting Ms Anstee through the leg.
The bullet broke her femur and exited through the front of her thigh.
Mr Coker suffered a bullet graze to his leg.
His father John Coker said the first he heard about it was a text message from his son at 4am (AEDT) on Thursday saying "call me now".
"My wife said to me: 'I bet their luggage has gone astray'," Mr Coker told the Seven Network.
"So I rang him and I said: 'Oh, Dave, it's dad what's up?' and he said: 'I've been shot'.
"I must say that I just sort of went cold.
"Then he said: 'But I'm OK, but Katie's in intensive care'.
"He said can you get here and then he started to tell me what was happening."
Mr Coker said he then began calling the Department of Foreign Affairs and Trade (DFAT) to see about rushing through some visas to get over to help his son.
David and Katie's mothers have plans to get out to Mumbai as early as Friday evening, unless DFAT advises them strongly otherwise.
"We're all worried about their (the mothers') safety but I think their prime consideration is, of course, David and Katie and what support they can provide for them," Mr Coker said.
"The vast information we got is that the travel insurers - and thank goodness they had travel insurance - are trying to Medivac them out and that looks like it might be Sunday if Katie's stable.
"In which case we have to decide whether (the mothers) try and get there by Friday evening because, I understand, it's still a fairly unstable situation, so we're worried."
Mr Coker said David and Katie were still in hospital where he was having X-rays looking for shrapnel.
"He was more concerned about Katie and was saying that she was resting comfortably," he said.
"She'd had an operation and her leg had been put in traction.
"(Doctors were) working out whether they had to do a further operation to stabilise the injuries that she had but he said that she was comfortable at least."
David Coker has previously described how he grabbed Ms Anstee and got her out of the hotel when she couldn't walk.
He said their attackers appeared to be very young.
"They looked just like boys. They are on a rampage - it's full-on," he told The Courier-Mail newspaper.
Mr Coker's uncle Michael Fellows told the Brisbane Times that the couple, who met at Australian National University in Canberra several years ago, were on the first day of a long holiday.