orientjs - how to perform bulk insert

orientdb.insert()
        .into('User')
        .set({name: 'John', surname: 'Smith'})
        .all()
        .then(function(result) {
  ...
}, function(error){
  ...
})

This is the way to insert a single vertex in OrientDb via orientjs. How to insert multiple objects at once?

The following query

orientdb.insert()
        .into('User')
        .set([{name: 'John', surname: 'Smith'}, {name: 'Harry', surname: 'Potter'}])
        .all()
        .then(function(result) {
      ...
    }, function(error){
      ...
    })

inserts only the last element ({name: 'Harry', surname: 'Potter'})