Diesel and gasoline prices continued to fall last week, but the weekend's terrorist attacks in Paris and Beirut caused crude oil prices to jump.

Monday's weekly numbers from the Department of Energy show the national average on-highway price of a gallon of diesel was $2.482, down 2 cents from a week earlier and $1.179 lower than a year ago.

The highest average price was on the West Coast, at $2.695 a gallon, led by California's $2.769 per gallon. The Central Atlantic region wasn't far behind, at $2.609 a gallon.

The lowest average diesel prices were found in the Gulf Coast region at $2.304 per gallon.

The national average for a gallon of regular gasoline was $2.178. That's down 5.7 cents from a week earlier and 71.6 cents lower than a year ago.

The West Coast region had the highest average gasoline price, at $2.636, while the lowest was in the Gulf Coast region, at $1.926.

Crude oil prices Monday stopped their downward spiral after the U.S. benchmark, West Texas Intermediate, came very close to what The Wall Street Journal called "the psychologically key $40-a-barrel level."

The price on the New York Mercantile Exchange settled the day Monday up $1, or 2.5%, at $41.74 a barrel.

Jitters about what's going on in the key oil-producing region of the Middle East likely caused oil prices to rise, as other countries step up their efforts to fight ISIS, the Islamic State, following the Paris terror attacks.