KATMANDU, Nepal — Maoist opposition leaders in Nepal threw chairs and microphones at members of the governing parties on Tuesday at a meeting of lawmakers working to draft a Constitution on deadline. Three lawmakers and about a dozen security guards were wounded.

Hours later, the Maoists, who won only a small fraction of seats in elections for the Constituent Assembly in 2013, strictly enforced a nationwide strike that shut down traffic, schools and markets.

The opposition alliance, which is led by the Maoist faction of the Communist Party, wants the new Constitution to carve provinces in Nepal along ethnic lines, a provision the governing coalition adamantly opposes. Regional parties representing members of the Madhesi ethnic group are seeking to declare the southern plains a separate province.