An 11-year-old girl died Friday of suspected bird flu in eastern Turkey — days after her brother and sister succumbed to the disease — and their doctor said they probably contracted the illness by playing with dead chickens.

Prime Minister Recep Tayyip Erdogan said people urgently needed to be educated about keeping birds, and that during Friday prayers, imams would give instructions on protecting themselves.

The condition of a fourth ill child from the same family had improved considerably and he was no longer on a respirator, said Huseyin Avni Sahin, head physician at the hospital in the eastern city of Van, where the children were being treated. Three other people, however, were in serious condition, he told The Associated Press.

A hospital official said up to 30 other people were being treated for possible bird flu symptoms early Friday, as the government sent medicine to the area to combat a virus that appeared to be moving westward from eastern Asia. Five other people were admitted to a hospital in Diyarbakir, about 250 miles away, for possible bird flu.

Preliminary tests in Turkey indicated two of the siblings died of the H5N1 strain of bird flu. If confirmed by further testing, it would be the first human deaths from the strain outside eastern Asian areas, where more than 70 people have died from H5N1 since 2003. Samples were being sent to a British lab for confirmation.

Authorities are closely monitoring H5N1 for fear it could mutate into a form easily passed among humans and spark a pandemic.

The World Health Organization was doing tests to determine whether the bird flu cases resulted from human-to-human transmission, WHO spokeswoman Fadela Chaib said in Geneva. The tests were being conducted on samples from the first two victims at a British lab, where they arrived Thursday, and results are expected "in the next few days," she said.

Hulya Kocyigit, 11, died in a hospital in Van a day after her 15-year-old sister, Fatma Kocyigit, succumbed to the disease, Sahin said. Their brother, Mehmet Ali Kocyigit, 14, died Sunday. The four children were hospitalized with high fevers, coughing and bleeding in their throats.

The doctor said the youngsters most likely contracted the virus while playing with the heads of dead chickens infected with the disease. The children had reportedly tossed the chicken heads like balls inside their house in Dogubayazit, near the Iranian border.

"They played with the heads for days," Sahin said. "They were in very, very close contact with the dead chickens."

Another 25-30 people had come in to the hospital for blood tests, received medical care and left, a hospital official said on condition of anonymity because he was not authorized to speak to the media.

New bird flu cases in fowl were detected in five areas in eastern and southeastern Turkey, and authorities have culled 7,000 fowl in those areas, Agriculture Minister Mehdi Eker said.

The prime minister said people must be warned against concealing birds from health workers.

"We have a problem of education, which we have to overcome urgently," Erdogan said. "Chickens, turkeys, geese ... people should not hide them."

In the Kocyigits' hometown of Dogubayazit, teams went from house to house rounding up chickens, placing them in bags and taking them away to be culled. They warned children to keep away, after several of them, thinking it was a game, also tried to round up chickens.

The corridors of a hospital was packed with people wanting their children checked for bird flu.

"We're full here. Everyone is wondering if they've got it," Dr. Huseyin Yurtsever said, adding that he was sending suspicious cases to the hospital in Van.

Authorities in the southeastern province of Sanliurfa dispatched medical teams to the town of Hilvan, where bird flu in fowl has been detected, to deal with a similar panic in a clinic there.

A team of officials from WHO and the Food and Agriculture Organization were expected to arrive Friday in Turkey to assess the situation.

Officials tried to calm the rising fears.

"We don't expect the disease to contaminate a large number of people," Health Minister Recep Akdag said. "We don't expect a pandemic or anything like that in Turkey, but there is a real risk for people who are in close contact with fowl."

Eker said the problem of containing bird flu in eastern Turkey is aggravated by the fact that almost every house has fowl, which stay inside the homes at night when temperatures drop.

Most of those who have died from the disease so far were farm workers who came in close contact with fowl from Vietnam, Thailand and Indonesia.

Birds in Turkey, Romania, Russia and Croatia have recently tested positive for H5N1.

Authorities have said the virus was believed to have been brought by birds migrating from Caucasus regions.