ST. PAUL, Minn. (AP) - Police and firefighters across Minnesota are retiring in greater numbers, a development attributed to changes in the state pension rule.

About 300 officers and firefighters retire each year. But for the fiscal year ending June 30, there will be an estimated 600 retirements.

That's according to Public Employees Retirement Association of Minnesota.

The group says the higher numbers may reflect people who are moving up their retirement plans.

Under pension changes that became law last year, officers who wanted to retire before age 55 would have received smaller pension payments if they did so after May 31.

The retirements could lead to staffing shortages at police departments across the state. For example, 27 Minneapolis officers retired this month. That's about as many as retire in an average year.