* Yolanda (Haiyan) potentially strongest typhoon ever to make landfall
* Wind gust of about 300 kph (186 mph), whips up giant waves
* More than a million flee, take refuge in shelters
MANILA (UPDATED) - The strongest typhoon in the world this year and possibly the most powerful ever to hit land smashed into the Philippines on Friday, forcing more than a million people to flee, flooding villages and raising fears of widespread casualties.
Yolanda (international name Haiyan), a category-5 super typhoon, scoured the northern tip of Cebu province and headed northwest towards Boracay island, both tourist destinations, after lashing the central islands of Leyte and Samar with 275-kph (170 mph) wind gusts and 5-6 metre (15-19 ft) waves.
At least three people were killed and seven injured, national disaster agency spokesman Rey Balido told reporters in Manila. The death toll could rise as more reports arrive.
"The humanitarian impact of Haiyan threatens to be colossal," said Patrick Fuller, spokesman for the International Federation of Red Cross and Red Crescent Societies.
Power and communications in the three large islands of Samar, Leyte and Bohol were almost completely down but authorities promised to restore them within 24 hours.
Officials warned that more than 12 million people were at risk, including residents of Cebu City, which has a population of about 2.5 million, and areas still reeling from a deadly 2011 storm and a 7.2-magnitude quake last month.
"The super typhoon likely made landfall with winds near 195 mph (313 kph). This makes Haiyan the strongest tropical cyclone on record to make landfall," said Jeff Masters, director of meteorology at U.S.-based Weather Underground.
About a million people took shelter in 29 provinces, after President Benigno Aquino appealed to people in Haiyan's path to leave vulnerable areas, such as river banks, coastal villages and mountain slopes.
"Our school is now packed with evacuees," an elementary school teacher in Southern Leyte, who gave her name only as Feliza, told a radio station. Leyte and Southern Leyte are about 630 km (390 miles) southeast of Manila.
Energy Secretary Jericho Petilla reported a 3-metre (10-ft) flood in one village in Leyte. "There is zero communication at the moment," he told ANC television.
NO POWER, LANDSLIDES
"Roads are still impassable. There are some landslides," said Roger Mercado, governor of Southern Leyte province.
More than 100 coastal homes were flattened, while landslides destroyed houses in the hills, but his province had seen no casualties yet, he told Reuters.
In Samar province, links with some towns and villages had been cut, officials said.
"The whole province has no power," Samar Governor Sharee Tan told Reuters by telephone. Fallen trees, toppled electric poles and other debris blocked roads, she said.
Authorities suspended ferry services and fishing and shut 13 airports. Nearly 450 domestic, and eight international, flights were suspended.
Schools, offices and shops in the central regions were shut, with hospitals, soldiers and emergency workers preparing rescue efforts. Twenty navy ships and military aircraft including three C-130 cargo planes and helicopters were on standby.
"Power is off all across the island and the streets are deserted," said Lionel Dosdosa, an International Organization for Migration coordinator on Bohol island, the epicentre of an Oct. 15 earthquake that killed 222 people and displaced hundreds of thousands. He said power was off and streets were deserted.
At the Sandcastles Beach Resort in Boracay, guests stayed indoors. "The beach is abandoned. The winds are whistling unceasingly, so we secured our homes and the resort," Jenelyn Castro, one of the resort's staff, said by telephone.
The state weather bureau said Haiyan was expected to move past the Philippines on Saturday and out over the South China Sea, where it could strengthen even further and hit Vietnam.
Meteorologists in Vietnam said it could be the country's strongest storm ever. Evacuations had already begun, the state-run Voice of Vietnam radio said.
The world's strongest recorded typhoon, cyclone or hurricane to make landfall was Hurricane Camille in 1969, which hit the southern U.S state of Mississippi with 305 kph (190 mph) winds, said Weather Underground's Masters.
An average of 20 typhoons hit the Philippines every year.
Last year, Typhoon Bopha flattened three towns on Mindanao, killed 1,100 people and caused damages of more than $1 billion.
Haiyan is the second category 5 typhoon to hit the Philippines this year after Typhoon Usagi in September.