The board of trustees may invest the pension fund in the name of "Board of Trustees of the Firemen's Fund of the City of __________" in any of the following:
(1) Obligations of the United States or obligations fully guaranteed both as to principal and interest by the United States;
(2) Obligations of the Federal intermediate credit banks, Federal home loan banks, Federal National Mortgage Association, banks for cooperatives and Federal land banks and any notes, bonds, debentures, or other similar obligations, consolidated or otherwise, issued by farm credit institutions pursuant to authorities contained in the Farm Credit Act of 1971 (Public Law 92-181);
(3) Obligations of this State;
(4) In the shares of Federal savings and loan associations and State-chartered building or savings and loan associations in which deposits are guaranteed by the Federal Savings and Loan Insurance Corporation, not to exceed the amount covered by insurance.
All such securities shall be deposited by the treasurer with other securities of the city and shall be subject to the order of the board of trustees.