The accident happened between Pauri Rd - the turnoff to Whanganui Prison - and Marangai Rd.
SH3 was closed until 10am while the crash scene was investigated by the police serious crash unit. Police later confirmed the deaths have been referred to the coroner.
A Central Districts Police spokesperson said: "It's too early to determine exactly what may have caused this crash, and until that investigation is complete police will not be speculating on any aspect."
Earlier reports said Ms Hurley was the designated sober driver of a car returning from Palmerston North. Also aboard were her partner Mr Leslie and two other friends.
Mr Leslie was airlifted to Palmerston North Hospital where he was reported to be in a serious condition yesterday. Another passenger, Hamish Kennedy, 25, was admitted to Whanganui Hospital's intensive care unit with broken ribs and sternum, while a third friend was airlifted to Wellington Hospital with serious injuries. No update on their conditions was available at press time.
All three were trapped in the wreckage until Whanganui Fire Service crews were able to cut them free.
While she and Mr Leslie were life partners, they were also business partners and owned and operated Maggies Pies in Cross St, Castlecliff.
A worker at the nearby service station, who did not want to be identified, said the couple had been in the pie shop "for a year or two".
"They were a really nice couple. They'd get their bread and other stuff from us," he said.
"This is really shocking news."
Ms Hurley's friends and family have posted tribute messages on Facebook, all of them remembering a "beautiful young lady".
One said she could not believe Ms Hurley was gone: "Gone too young still can't believe it is real". Taylor Rhodes wrote: "You were so beautiful inside and out, it's scary how things can just change in seconds and even minutes. Rest easy Emily and Baby Jake xxx ... "
A former teacher remembered Ms Hurley "as just the sweetest little girl".
