Pacific Investment Management Co. and BlackRock Inc. are among bond investors seeking a court order blocking Richmond, Calif., and Mortgage Resolution Partners LLC from seizing mortgages through eminent domain, saying the initiative would hurt savers and retirees, Bloomberg News reported yesterday. The city’s plan is unconstitutional, according to a complaint filed yesterday by mortgage-bond trustees in federal court in San Francisco. The trustees, Wells Fargo & Co. and Deutsche Bank AG, were directed to take the action by investors in the debt that also include Jeffrey Gundlach’s DoubleLine Capital LP, said John Ertman, a partner at Ropes & Gray LLP. The plan advanced last month with Richmond backing offers to buy 624 loans, making it the first city to push the idea so far forward. Those offers would need to be refused before the city could follow through with its mayor’s vow to invoke its potential powers to force sales of the mostly non-delinquent loans, so that homeowners could get their debt balances cut to less than the current values of their properties. The program would harm owners of mortgage bonds by paying them too little for loans, as well as damage communities by drying up lending, at least 18 trade groups representing asset managers, bankers, real-estate firms and builders have said in past statements. Costs to investors could exceed $200 million just on loans in Richmond, according to the complaint.