LONG BEACH, Calif. (AP) _ Construction officially began Thursday on a light rail mass-transit line that will run 21 miles from Long Beach to downtown Los Angeles.

Los Angeles Mayor Tom Bradley and Jacki Bacharach, chairwoman of the Los Angeles County Transportation Commission, were among those taking part in a groundbreaking ceremony at a North Long Beach site that will be the system's maintenance yard. The line, which will include 22 stops, is scheduled to open in October 1989.

The line is being financed by a half-cent county sales tax approved by the voters in 1980 as Proposition A. The rail cars will ride on double tracks and be powered by an overhead electric line.

It's part of a planned 150-mile network to connect communities in the Los Angeles basin to the proposed Metro Rail subway.