Assigning random values using ForEach to array doesnt work, but for statement works fine?

Assigning random values using ForEach to array doesnt work, but for
statement works fine?

If I use the foreach loop to assign values to an array randomly, it
assigns all 0's. But if change it to a normal for loop, it works fine.
Like below
Random random = new Random();
int[] a = new int[10];
for (int i = 0; i < 10; i++)
{
a[i] = random.Next(0, 10);
}
foreach (var item in a)
Console.WriteLine(item);
The output is fine, values are random
5
8
...
But, if I use a foreach loop to assign random values, the FIRST array item
has a random value and the rest are ALWAYS 0.... Why would that be?
foreach (var item in a)
{
a[item] = random.Next(0, 10);
}
foreach (var item in a)
Console.WriteLine(item);
this produces
8
0
0
0... all zeros follow
Why would a normal for loop work fine, but not a foreach loop? The same
foreach loops prints the values fine ?
Thank you