Randomly select n elements from Array in Scala

I want to select n unique elements from array where size of my array is normally 1000 and value of n is 3. I want to implement this in iterative algorithm where iterations are around 3000000 and I have to get n unique elements in each iteration. Here are some available solutions I fond but I can not use them due to their draw backs as discussed below.

import scala.util.Random
val l = Seq("a", "b", "c", "d", "e")
val ran = l.map(x => (Random.nextFloat(), x)).sortBy(_._1).map(_._2).take(3)

This method is slower as have to create three arrays and Sorting the array too.

 val list = List(1,2,3,4,5,1,2,3,4,5)
 val uniq = list.distinct
 val shuffled = scala.util.Random.shuffle(uniq)
 val sampled = shuffled.take(n)

Two arrays are generated and Shuffling the large array is slower process.

 val arr = Array.fill(1000)(math.random )
 for (i <- 1 to n; r = (Math.random * xs.size).toInt) yield arr(r)

This is faster tecnique but some times returns same element more than one time. Here is an output.

val xs = List(60, 95, 24, 85, 50, 62, 41, 68, 34, 57)
for (i <- 1 to n; r = (Math.random * xs.size).toInt) yield xs(r)

res: scala.collection.immutable.IndexedSeq[Int] = Vector( 24 , 24 , 41)

It can be observed that 24 is returned 2 times.

How can I change last method to get unique elements? Is there any other more optimal way to perform same task?