Cairo (CNN) -- An official investigation into the cause of a balloon accident that killed 19 people in Egypt could take two weeks, the governor of Luxor province said Wednesday.
The Tuesday accident was the world's deadliest hot air balloon accident in at least 20 years.
Preliminary investigations confirmed no foul play was involved when gas canisters aboard the balloon exploded, causing it to plummet about 1,000 feet (300 meters) to the ground, Gov. Ezzat Saad said.
As the balloon prepared to land Tuesday morning, an explosion pierced the air, followed by billowing smoke.
"My first thought was that it was sugar cane that was burning," said Christopher Michel, a photographer who was a passenger in another balloon at the time.
Smoke from the burning sugar cane painted the ancient city of Luxor below with an eerie haziness.
But the concern shown by the balloon pilot and the blaring sirens from emergency vehicles told Michel that something was wrong. He could not imagine the extent:
One of the balloons had exploded, and its 21 passengers and operators plummeted about 1,000 feet (300 meters) to the ground.
"This juxtaposition of this great beauty and this wonderful country and this horrible tragedy is just really shocking," Michel said. "We all feel terrible."
It was an early, dark morning, Michel said, and uneventful for 45 minutes until they started to descend. He was overlooking mud-brick buildings and fields, with the Valley of the Kings in the distance, when the explosion shattered the quiet of the morning.
Passengers in the balloon included 19 foreign tourists: nine from Hong Kong, four from Japan, three from Britain, two from France and one from Hungary, officials said.
An Egyptian pilot and another Egyptian were also aboard, Luxor province spokesman Badawi al-Masri said.
Balloon rides offering panoramic aerial views of the Nile River and the ancient temples of Karnak and Hatshepsut are a popular tourist attraction in Luxor, about a nine-hour drive southeast of Cairo.
"You can see Valley of the Kings in the background bordered by farmland," Pauline Liang of Vancouver, Canada, told CNN's iReport last year. "Below were banana farms, and behind us was the city of Luxor. There was a great contrast between desert landscape, lush farmland and urban development."
Tuesday's crash prompted the governor to ban all hot air balloon flights until further notice.
Luxor is among Egypt's top tourist draws. Visitors go to see ancient temples and tombs, and travel sites often recommend the hot air balloon trips.
The last hot air balloon accident in Luxor occurred in 2009, when 16 foreign tourists were injured after a balloon struck a cell phone transmission tower.
Until Tuesday's incident, the deadliest accident in recent memory took place in 1989, when 13 people were killed as two hot air balloons collided in Australia.
Journalist Adam Makary contributed from Cairo, and CNN's Saad Abedine and Mariano Castillo reported from Atlanta