JavaScript: group array of objects by property in an object

if I have a js array like below, is there a simple way to re-group the array values by age? I tried to reduce it to an array but it did not help. it’s re-grouped with age or name’s

let employees = [
 {
  firstName:"Zion",
  lastName: "Rosy",
  age: 25,
  joinedDate:"January 24, 2020",
 },

 {
  firstName: "Ana",
  lastName: "Rosy",
  age: 25,
  joinedDate: "January 15, 2019",
 },

 {
  firstName: "Zion",
  lastName:"Albert",
  age: 30,
  joinedDate:"February 15, 2011",
 },
];

To re-group by age like this:

let organizedByAge =
 {
  25: [
 {
  firstName:"Zion",
  lastName: "Rosy",
  age: 25,
  joinedDate:"January 24, 2020",
 },
 {
  firstName: "Ana",
  lastName: "Rosy",
  age: 25,
  joinedDate: "January 15, 2019",
 },
  ],

  30: [
   {
    firstName:"Zion",
    lastName:"Albert",
    age: 30,
    joinedDate:"February 15, 2011",
   },
  ],
 };