Orders of medium-duty vehicles remained strong in April, even though they fell 10% from a March peak and came in 12% higher than a year ago, according to ACT Research.

About 20,100 orders for Class 5-7 vehicles were placed during the month, according to preliminary estimates.

"The healthy medium-duty order trend, which began in September 2015, continued in April, although at a modestly reduced rate," said Kenny Vieth, president and senior analyst for the firm. "Orders fell 10% sequentially from one of the best order months experienced cycle-to-date."

Medium-duty demand was bolstered by a decent jobs market and rising incomes, which support discretionary spending and improved housing and automotive sales activity, Vieth said.