Mountaineers seeking to scale the world's tallest peak have called off this year's Everest season after 18 people died when last month's quake triggered avalanches on the mountain.
Dambar Parajuli, president of Expedition Operators' Association of Nepal, said there were no climbers or Nepali sherpa guides at Base Camp.
"All of them have already left," Parajuli said.
In Lukla, the departure point for treks to Everest, buildings cracked and small landslides were triggered when the ground shook.
Read MoreNepal earthquake has 'shaken people up'
Susana Perez from Madrid was on a 10-day trek with her husband to Island Peak in the Everest region and was about to reach Lukla.
"We saw the mountain in front of us fall down - earth and rocks. There were some houses underneath but it was not clear if they were hit," Perez said.
In Kathmandu, people panicked and rushed outdoors when the tremors began at around 12.30, Reuters witnesses said. The quake was followed by at least half a dozen aftershocks, including one as big as 6.3 magnitude.
Parents clutched children tightly, and hundreds of people frantically tried to call relatives on mobile phones. Shopkeepers closed their stores and the streets were jammed with people rushing to check on their families.