Air traffic controllers lost track of Malaysia Airlines Flight MH370 not long after it left Kuala Lumpur, the capital of Malaysia, on its way to Beijing. More than half the passengers were Chinese nationals.

"We have no idea where this aircraft is right now," Malaysia Airlines Vice President of Operations Control Fuad Sharuji said on CNN's "AC360."

There's even confusion about where the plane might have gone down.

Vietnamese and Chinese state media, both citing Vietnam's military, reported the plane crashed off the southern coast of Vietnam.

But the reports are incorrect, said Malaysia's acting transport minister, Datuk Seri Hishammuddin Hussein. "The CA (Civil Aviation Authority) says that is not true, and our foreign office says it is not true," he said.

Later, China's state-run CCTV reported that Vietnam's National Search and Rescue Center said the missing plane might have crashed at the overlapping waters between Malaysia and Vietnam.

China, Vietnam, Singapore, and Malaysia are conducting search and rescue operations south of Tho Chu island in the South China Sea, reported Xinhua, China's official news agency. Ships, helicopters and airplanes are being utilized.

Grief, especially in China

Relatives of the 154 Chinese nationals on board gathered Saturday at a hotel complex in the Lido district of Beijing as a large crowd of reporters gathered outside.

"My son was only 40 years old," one woman wailed as she was led inside. "My son, my son. What am I going to do?"

Family members are kept in a hotel conference room, where media outlets have no access. Most of the family members have so far refused to talk to reporters.

The Boeing 777-200 departed Kuala Lumpur International Airport at 12:41 a.m. and was expected to land in Beijing at 6:30 a.m., a 2,300-mile (3,700 kilometer) trip. It never arrived.

The plane carried 227 passengers, two of them infants, and 12 crew members, the airline said. Air traffic control in Subang, in Malaysia, had last contact with the plane.