Federal safety agency has expanded its investigation of Tesla’s Autopilot system.

The federal government’s top auto-safety agency is significantly expanding an investigation into Tesla and its Autopilot driver-assistance system to determine if the technology poses a safety risk.

The agency, the National Highway Traffic Safety Administration, said Thursday that it was upgrading its preliminary evaluation of Autopilot to an engineering analysis, a more intensive level of scrutiny that is required before a recall can be ordered.

The analysis will look at whether Autopilot fails to prevent drivers from diverting their attention from the road and engaging in other predictable and risky behavior while using the system.

The NHTSA said it had not determined whether Autopilot has defects that can cause cars to crash while it is engaged.

The wider investigation covers 830,000 vehicles sold in the United States. They include all four Tesla cars — the Models S, X, 3, and Y — in model years from 2014 to 2021.

The agency’s preliminary evaluation focused on 11 incidents in which Tesla cars operating under Autopilot control crashed into emergency vehicles that were parked and had their lights flashing. In that review, NHTSA said Thursday, the agency became aware of 191 crashes — not limited to those involving emergency vehicles — that warranted closer investigation.

This is a developing story. Check for updates.