BETHESDA, Md. — Bethesda-Chevy Chase residents have warned the Montgomery County Council to think twice before turning downtown Bethesda into the Maryland equivalent of Tysons Corner. The council is considering adding 29-story buildings and 4.6 million square feet of residential and office space in a 20-year plan.

“This would rank Bethesda second to Baltimore in the number of very tall buildings and far ahead of Tysons Corner,” said Scott Fosler, mayor of Chevy Chase.

The county council held the first of three public hearings Tuesday night on the Bethesda Downtown Plan, approved by the Montgomery County Planning Board in July.

“We have recommended higher height limits throughout the plan,” the planning board’s Casey Anderson told the council. He added, “This plan does make unprecedented commitments of real resources and, I think, credible mechanisms for achieving some of the goals of parks and open space, affordable housing and, also, better design.”

But residents lined up to give the plan their thumbs-down, and told the council that building heights should be scaled back, park space increased and density reduced.

“That’s equivalent to adding one and one-third Pentagons right in downtown Bethesda,” said Alison MacFarlane, a resident of East Bethesda.

Residents also complained that the park space in the plan reaches just 4 percent of the area.

“In comparison, Washington, D.C., has 21.9, percent park land and Arlington 11.2 percent,” said Maj-Britt Dohlie, another resident of East Bethesda.

Residents also demanded the council create a citizens advisory panel on Bethesda development before approving the planning board’s work.