(Reuters) – Elon Musk’s The Boring Company has raised $675 million in Series C funding round, which now values the tunneling enterprise at $5.675 billion, the company said https:// on Wednesday, adding that the proceeds will be used to ramp up its hiring across sectors.

The Austin, Texas-based company, which plans to expand its workforce in engineering, operations, and production to scale up its Loop projects, said the funding round was led by Vy Capital and Sequoia Capital, with participation from Valor Equity Partners, Founders Fund, 8VC, Craft Ventures, and DFJ Growth.

Boring Company had launched its commercial tunnel project in Las Vegas last June to transport visitors through the city’s Convention Center using human-driven Tesla (NASDAQ:) vehicles.

Musk, who also leads electric vehicle maker Tesla Inc and rocket company SpaceX, is seeking to revolutionize transportation by sending passengers packed into pods through an intercity system of giant, underground vacuum tubes known as the hyperloop.

Musk had earlier sold Boring Company hats and flamethrowers to raise funds.

Last week, billionaire Musk took aim at Twitter Inc (NYSE:) with a $43 billion cash takeover offer. His offer price of $54.20 per share was a 38% premium to Twitter’s April 1 close, the last trading day before his 9.1% stake in the social media platform was made public.