Two Washington-area banking firms posted third-quarter gains in net income yesterday.

American Security Corp., parent of American Security Bank N.A., reported yesterday its third-quarter net income grew 11.9 percent over the like period last year.

Net income was $7.2 million ($1.98 a share) compared with $6.4 million ($1.79) in 1980. For the nine months ended Sept. 30, net income was $20.2 million ($5.60) compared with $17.9 million ($4.96) through three quarters of 1980.

Total assets at the end of the third quarter were $2.8 billion, and deposits were $2.1 billion, compared with assets of $2.5 billion and deposits of $2.0 billion at the same time last year, the bank reported.

"Our results for both the third quarter and the year to date are very much in line with our performance goals," said W. Jarvis Moody, chairman of American Security Corp.

Third-quarter net income at Citizens Bank and Trust Co. of Maryland jumped 64 percent to $3.6 million ($2.22) from $2.2 million ($1.37) in 1980. For the nine months ended Sept. 30, net income was $9.9 million ($6.13) compared with $6.7 million ($4.16) last year. On Sept. 30, deposits were $597.5 million and assets were $708.1 million.

National consumer electronics retailer Wards Co. Inc. of Richmond, owner of Circuit City stores, reported second-quarter net income skidded 76 percent to $79,000 (4 cents) from $325,000 (20 cents) this time last year.

During that time, however, revenues climbed to $37.3 million from 1980's $29.2 million, a 28 percent gain.