LOS ANGELES (AP) — More rain fell Monday on parts of Southern California after causing mudflows over the weekend, helping firefighters but boosting the risk of toxic ash runoff in areas scorched by Los Angeles-area wildfires.

A slow-moving low-pressure system will linger over the Southwest, bringing steady rain through at least Monday.

The charred soil left by the wildfires could create conditions ripe for mudslides because the rain, which will last into Monday, will just run off, forecasters said.

Rain was falling across Southern California on Sunday, bringing some relief to thousands of firefighters battling multiple major blazes for nearly a month in the Los Angeles area, but also prompting new threats of floods and mudslides across burn-scarred lands.

Rain falling on Southern California is expected to aid firefighters mopping up multiple wildfires. But potentially heavy downpours on charred hillsides could bring new troubles such as toxic ash runoff.

"That could be enough to create debris flows." The rain started along the Central Coast before moving into Ventura and LA counties in the evening. It was forecast to increase throughout the weekend and possibly last into early Tuesday,