Republican Donald Trump won Indiana, the home state of his running mate Mike Pence, while Hillary Clinton took the northeastern state of Vermont, in the first results of Tuesday's US presidential election, television networks projected.

It was still too early to determine a winner in three of the first six states to close their polls -- Republican-leaning South Carolina and Georgia, and the key battleground of Virginia, the networks said.

Those first results give the 70-year-old Republican billionaire an early lead in the count of Electoral College votes -- 19 to three for Clinton.

The lead in the running tally toward the magic number of 270 electoral votes needed to win the White House -- a majority of the 538 up for grabs -- was expected to change hands as the evening wore on in the closely contested election.