The deadly biker-gang shootout over the weekend in Texas might have been touched off when one motorcyle lowlife ran over another’s foot, police said Tuesday.

Cops had originally said Sunday’s bloodbath — which killed nine people and wounded 18 — started with a shoving match inside a bathroom of Twin Peaks restaurant.

Now police said the root of that tussle-turned-shootout might have been outside in the shopping center’s parking.

“I have additional information this morning that may go beyond a parking incident to somebody had their foot run over and started the disturbance in the parking lot,” Waco police Sgt. Patrick Swanton told reporters Tuesday.

Police also revealed that another gang — not invited to Sunday’s alleged biker-gang peace summit — crashed the meeting, possibly fueling tensions.

“We know an additional biker gang that was not invited to this meeting showed up,” Swanton said. “Hence, what we were calling somewhat of a turf war, if you will.”

Cops are still struggling to pinpoint the exact cause of the deadly gunfight because witnesses “are not being honest with us,” Swanton said.

Police have declined to identify all the gangs involved in Sunday’s shootout.

But the Dallas Morning News has reported that all nine dead bikers came from the Bandidos and Cossacks gangs and they were the primary combatants.

Dallas attorney and motorcycle buff William Smith said he’s previously met groups involved in Sunday’s shootout and insisted they’ve always been peaceful.

Smith said he’s consulted with them on helmet laws, other motorcycle regulations and safety issues.

“In my 18 years of attending, I’ve never seen anything like this, not even a dust-up — not even cross words,” Smith told Morning News. “That’s not what this is.”

About 170 biker gang members remained in custody Tuesday, held in lieu of $1 million bail, and charged with engaging in organized criminal activity. No one has yet been charged with murder.

Three defendants were let out when their bail was mistakenly lowered to $50,000, the Waco Tribune reported.