Section 89B. If a member of the police or fire force of any city or town is killed or dies from injuries received, or dies as a natural and proximate result of undergoing a hazard peculiar to his employment, while in the performance of his duty, and it shall be proved to the satisfaction of the appropriate public authority as hereinafter defined that such death was the natural and proximate result of an accident occurring, or of undergoing a hazard peculiar to his employment, while he was acting in the performance and within the scope of his duty, and the majority of the members of a board consisting of two physicians designated by the public authority hereinafter defined, and one physician to be designated by the commissioner of public health, who shall serve as chairman of the board, shall certify to the appropriate public authority that the death was the natural and proximate result of said injury or hazard, there shall, except as hereinafter provided, be paid out of the treasury of such body politic and corporate, to the following dependents of such deceased person the following annuities:—

To the widow, so long as she remains unmarried, an accidental death benefit allowance to consist of a yearly amount of annuity equal to two thirds of the annual rate of regular compensation of such police officer or fire fighter on the date such injury was sustained or such hazard was undergone, or equal to two thirds of the average annual rate of his regular compensation for the twelve-month period for which he last received regular compensation immediately preceding the date of his death, whichever is greater, increased in either case by three hundred and twelve dollars for each child of such deceased person during such time as such child is under the age of eighteen or over said age and physically or mentally incapacitated from earning; and if there is any such child and no widow, or the widow later dies, such an annuity as would have been payable to the widow had there been one or had she lived, to or for the benefit of such child, or of such children in equal shares, during the time aforesaid; and if there is any such child and the widow remarries, in lieu of the aforesaid annuity to her, an annuity of five hundred and twenty dollars to or for the benefit of each such child during the time aforesaid; and if there is no widow and no such child, an annuity not exceeding one thousand dollars to or for the benefit of the father or mother of the deceased, if such father or mother was dependent on him for support at the time of his death, during such time as such beneficiary is unable to support himself or herself and does not marry.

No payment shall be made under this section unless and until there is on file in the office of the city auditor, town accountant or officer having similar duties a copy of the marriage certificate of the widow, a record of the birth of each dependent child under age eighteen, and a medical certificate for each dependent child who is physically or mentally incapacitated from earning. The city auditor, town accountant or officer having similar duties shall annually require, for the purpose of supporting continuance of payments authorized under this section, such further certificates as may be necessary to evidence that a widow has not remarried or a child over eighteen continues physically or mentally incapacitated from earning.

The members of said board, to be designated by the public authority and the commissioner of public health, as aforesaid shall be so designated within thirty days after the filing of an application for an annuity hereunder, and said members shall make their report within sixty days after their appointment. The total amount of all such annuities shall not, except as hereinafter provided, exceed the annual rate of compensation received by such deceased person on the date such injury was sustained or such hazard was undergone, or equal to the average annual rate of his regular compensation for the twelve-month period for which he last received regular compensation immediately preceding the date of his death, whichever is greater. If such deceased person was a reserve, intermittent or special policeman or a reserve or call fireman of a city or town, and at the time he was killed, or at the time he received the injuries or underwent the hazard resulting in his death was performing duty to which he was assigned or called as such policeman or fireman, the annuity shall be based on the annual rate of compensation payable to a regular or permanent member of the police or fire force thereof, as the case may be, for the first year of service therein.

The benefits provided under this section shall be in the alternative for the benefits, if any, provided by any other provision of law; and the widow, or if there is no widow, the legal representative of the children entitled thereto, if any, otherwise the father or mother in the order named, shall elect which benefits shall be granted. Such election shall be made in writing and shall be filed with the board or authority in charge of granting the benefits under the other provision of law, and shall not be subject to change or revocation after the first payment of any benefit under this section; and any person receiving benefits under this section shall not at the same time receive benefits of like nature under any other provision of law.

In the case of a member of the police or fire force of a city, within thirty days after receiving a medical report on such member from the medical board the mayor shall file said report with or without recommendations to the city council, and they shall act thereon within sixty days.

The words ''appropriate public authority'' as used in this section shall mean the appropriate retirement board, established under section twenty, or, if there is no such board in the case of a town, the selectmen.

The provisions of section ninety-four shall not apply to annuities granted under this section.

This section shall become effective in a city having a Plan E or Plan D charter when accepted by a majority of the members of the city council, and in the case of other cities, by vote of the city council subject to the provisions of the charter, and in a town, by a majority vote at the annual town meeting.