TEHRAN, Iran — The deaths of Ladan and Laleh Bijani sent a wave of grief and shock across their homeland Tuesday.

Some Iranians pulled off the road upon hearing the news. Many cried out in shock. Others — at work, at restaurants, in their homes — simply wept.

The 29-year-old twins, born joined at the head, died Tuesday within 90 minutes of each other shortly after they were separated during surgery in Singapore.

"It's a national tragedy," said Ahmad Mahmoudi, a photographer in Tehran.

Housewife Noushin Nowrouzi parked her car after she heard the news on the radio so she could cry in peace.

Zari Bijani, the twins' older sister, fainted when state television interrupted normal programming to announce Ladan's death.

"Is my beloved Ladan really not with us anymore?" she cried out seconds before she was overcome.

The government sent its condolences to the family, saying it hoped progress in medical science would make such complicated surgery possible in the future.

It was the first time surgeons tried to separate adults joined at the head. The surgery has been performed successfully since 1952 on infants, whose brains can more easily recover.

The twins were aware of the operation's high risks but had pressed for the surgery anyway.

Ladan, the more talkative of the twins, had wanted to continue studying law and become a lawyer. Laleh, also a law school grad because she had little choice in the matter, had hoped to become a journalist.

On Tuesday, diplomats were arranging for the return of their bodies to Iran for burial — in separate caskets.

"At least we helped them achieve their dream of being separated," said Dr. Keith Goh, the lead surgeon.

Over three days, the team of 28 doctors and about 100 medical assistants repeatedly encountered surprises that preoperative scans and tests couldn't detect. The skullbone was denser and harder to cut than expected, the twins' distinct brains had fused together with tissue and their blood pressures and brain pressures proved unstable.

Ultimately, it was the unpredictable changes in how their blood flowed, and surgeons' inability to cope with those changes, that killed the sisters, Goh said.

The parents of the twins, Dadollah Bijani and Maryam Safari, thanked Iranians for praying for their children.

The sisters were born into a poor family of 11 children in Firouzabad, southern Iran, but grew up in Tehran under the care of doctors.

Their struggle for independence struck a chord in the nation. Television devoted many programs to the twins. Newspapers published page after page about their lives and the lengthy operation.

"I rarely watch television. But I've routinely been watching television in the past few days to closely follow the news on the twins," said Mohammad Hashemzadeh, a 39-year-old employee at the Ministry of Energy who stopped work as the television announced Ladan's death.

Before the operation, Ladan — who was named for a Persian rose that grows in rocky places — beamed confidence.

"If God wants us to live the rest of our lives as two separate, independent individuals, we will," she said.

Her sister's name, Laleh, means tulip in Persian.

"Both of them wanted either death or separation," Zoreh Nezami, a housewife, said after hearing about Ladan's death. "Laleh would have died of grief even if she had survived," she said.