Are C# arrays thread safe?

In particular

1. Create a function to take an array and an index as parameters.
2. Create a n element array.
3. Create a n count loop.
4. Inside the loop on a new thread assign a new instance of the object to the array using the indexer passed in.

I know how to manage the threads etc. I am interested in know if this is thread safe way of doing something.

 class Program
{
    // bogus object
    class SomeObject
    {
        private int value1;
        private int value2;

        public SomeObject(int value1, int value2)
        {
            this.value1 = value1;
            this.value2 = value2;
        }
    }

    static void Main(string[] args)
    {

        var s = new SomeObject[10];
        var threads = Environment.ProcessorCount - 1;
        var stp = new SmartThreadPool(1000, threads, threads);
        for (var i = 0; i < 10; i++)
        {
            stp.QueueWorkItem(CreateElement, s, i);
        }

    }

    static void CreateElement(SomeObject[] s, int index)
    {
        s[index] = new SomeObject(index, 2);
    }
}